[llvm] [cmake] Forward MacOS sysroot to runtimes when not crosscompiling (PR #182501)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-sparc64-linux` running on `debian-stadler-sparc64` while building `llvm` at step 6 "build stage 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/114/builds/610

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (build stage 1) failure: 'ninja' (failure)
...
[2785/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCUnusedIVarsChecker.cpp.o
[2786/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/NullabilityChecker.cpp.o
[2787/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCSelfInitChecker.cpp.o
[2788/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/PointerSubChecker.cpp.o
[2789/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCContainersChecker.cpp.o
[2790/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCSuperDeallocChecker.cpp.o
[2791/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/PaddingChecker.cpp.o
[2792/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/PutenvStackArrayChecker.cpp.o
[2793/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/GenericTaintChecker.cpp.o
[2794/4313] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/RetainCountChecker/RetainCountDiagnostics.cpp.o
FAILED: [code=1] tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/RetainCountChecker/RetainCountDiagnostics.cpp.o 
/usr/bin/c++ -DCLANG_EXPORTS -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/stage1/tools/clang/lib/StaticAnalyzer/Checkers -I/var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/lib/StaticAnalyzer/Checkers -I/var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/include -I/var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/stage1/tools/clang/include -I/var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/stage1/include -I/var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-maybe-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-dangling-reference -Wno-redundant-move -Wno-pessimizing-move -Wno-array-bounds -Wno-stringop-overread -Wno-dangling-pointer -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -fno-common -Woverloaded-virtual -O3 -DNDEBUG -std=c++17 -UNDEBUG -fno-exceptions -funwind-tables -fno-rtti -MD -MT tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/RetainCountChecker/RetainCountDiagnostics.cpp.o -MF tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/RetainCountChecker/RetainCountDiagnostics.cpp.o.d -o tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/RetainCountChecker/RetainCountDiagnostics.cpp.o -c /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.cpp
cc1plus: error: expected unqualified-id before ‘=’ token
In file included from /usr/include/c++/15/bits/postypes.h:42,
                 from /usr/include/c++/15/iosfwd:44,
                 from /usr/include/c++/15/bits/shared_ptr.h:52,
                 from /usr/include/c++/15/memory:82,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/llvm/include/llvm/Support/Casting.h:20,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/include/clang/Basic/LLVM.h:21,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/include/clang/AST/APValue.h:16,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/include/clang/AST/Stmt.h:16,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/include/clang/Analysis/PathDiagnostic.h:16,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.h:17,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.cpp:14:
/usr/include/c++/15/cwchar:66:11: error: expected ‘;’ before ‘=’ token
   66 |   using ::mbstate_t;
      |           ^
      |           ;
cc1plus: error: duplicate ‘static’ specifier
/usr/include/c++/15/cwchar:285:14: error: ‘wcstof’ has not been declared in ‘std’
  285 |   using std::wcstof;
      |              ^~~~~~
/usr/include/c++/15/cwchar:288:14: error: ‘vfwscanf’ has not been declared in ‘std’
  288 |   using std::vfwscanf;
      |              ^~~~~~~~
/usr/include/c++/15/cwchar:291:14: error: ‘vswscanf’ has not been declared in ‘std’
  291 |   using std::vswscanf;
      |              ^~~~~~~~
/usr/include/c++/15/cwchar:294:14: error: ‘vwscanf’ has not been declared in ‘std’
  294 |   using std::vwscanf;
      |              ^~~~~~~
In file included from /usr/include/c++/15/string:44,
                 from /usr/include/c++/15/bits/locale_classes.h:42,
                 from /usr/include/c++/15/bits/ios_base.h:43,
                 from /usr/include/c++/15/streambuf:45,
                 from /usr/include/c++/15/bits/streambuf_iterator.h:37,
                 from /usr/include/c++/15/iterator:68,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/llvm/include/llvm/ADT/ADL.h:13,
                 from /var/lib/buildbot/workers/debian-stadler-sparc64/clang-sparc64-linux/llvm/llvm/include/llvm/ADT/SmallVector.h:17,

```

</details>

https://github.com/llvm/llvm-project/pull/182501