[clang] [LifetimeSafety] Revamp test suite using unittests (PR #149158)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-s390x-linux` running on `systemz-1` while building `clang` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/42/builds/5461

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
...
[417/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestJava.cpp.o
[418/1224] Linking CXX executable tools/clang/unittests/Basic/BasicTests
[419/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestMacroExpansion.cpp.o
[420/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestJson.cpp.o
[421/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestProto.cpp.o
[422/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestObjC.cpp.o
[423/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestRawStrings.cpp.o
[424/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestSelective.cpp.o
[425/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestTableGen.cpp.o
[426/1224] Building CXX object tools/clang/unittests/CMakeFiles/AllClangUnitTests.dir/Analysis/LifetimeSafetyTest.cpp.o
FAILED: tools/clang/unittests/CMakeFiles/AllClangUnitTests.dir/Analysis/LifetimeSafetyTest.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros /usr/bin/ccache /usr/bin/c++ -DEXPERIMENTAL_KEY_INSTRUCTIONS -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/tools/clang/unittests -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/unittests -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/tools/clang/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/stage1/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/llvm/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/unittests/Tooling -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/third-party/unittest/googletest/include -I/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/third-party/unittest/googlemock/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-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -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  -Wno-variadic-macros -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -std=c++17 -MD -MT tools/clang/unittests/CMakeFiles/AllClangUnitTests.dir/Analysis/LifetimeSafetyTest.cpp.o -MF tools/clang/unittests/CMakeFiles/AllClangUnitTests.dir/Analysis/LifetimeSafetyTest.cpp.o.d -o tools/clang/unittests/CMakeFiles/AllClangUnitTests.dir/Analysis/LifetimeSafetyTest.cpp.o -c /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/unittests/Analysis/LifetimeSafetyTest.cpp
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/unittests/Analysis/LifetimeSafetyTest.cpp:70:28: error: declaration of 'std::unique_ptr<clang::TestAST> clang::lifetimes::internal::{anonymous}::LifetimeTestRunner::TestAST' changes meaning of 'TestAST' [-fpermissive]
   70 |   std::unique_ptr<TestAST> TestAST;
      |                            ^~~~~~~
In file included from /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/unittests/Analysis/LifetimeSafetyTest.cpp:12:
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/clang/include/clang/Testing/TestAST.h:72:7: note: 'TestAST' declared here as 'class clang::TestAST'
   72 | class TestAST {
      |       ^~~~~~~
[427/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestTextProto.cpp.o
[428/1224] Building CXX object tools/clang/unittests/Format/CMakeFiles/FormatTests.dir/FormatTestVerilog.cpp.o
[429/1224] Linking CXX executable tools/clang/tools/extra/clangd/unittests/ClangdTests
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/149158