[clang] [llvm] [CMake] Add a linker test for -Bsymbolic-functions to AddLLVM (PR #79539)

[Rainer Orth via cfe-commits]

rorth wrote:

> @rorth Can you please check this on Solaris?

I've now tested the patch on `amd64-pc-solaris2.11` with both the native linker (which doesn't support` -Bsymbolic-functions`) and GNU `ld` (which does) as well as `sparcv9-sun-solaris2.11` with `/bin/ld`: no regressions on either, with the exception of the `gld` case: I get a failure in `Flang :: Driver/dynamic-linker.f90` which is unrelated, though: when configured with `-DCLANG_DEFAULT_LINKER=gld`, the test has
```
+ /var/llvm/local-amd64-release-stage2-A-flang-openmp-gcc14-gld/tools/clang/stage2-bins/bin/flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared -static /vol/llvm/src/llvm-project/local/flang/test/Driver/dynamic-linker.f90
+ /var/llvm/local-amd64-release-stage2-A-flang-openmp-gcc14-gld/tools/clang/stage2-bins/bin/FileCheck --check-prefixes=MSVC-LINKER-OPTIONS --implicit-check-not=MSVC-LINKER-OPTIONS-NOT /vol/llvm/src/llvm-project/local/flang/test/Driver/dynamic-linker.f90
/vol/llvm/src/llvm-project/local/flang/test/Driver/dynamic-linker.f90:24:24: error: MSVC-LINKER-OPTIONS: expected string not found in input
! MSVC-LINKER-OPTIONS: "{{.*}}link{{(.exe)?}}"
                       ^
```
while `flang` emits
```
          7:  "/usr/bin/gld" "-out:a.exe" "-libpath:lib/amd64" "-libpath:atlmfc/lib/amd64" "-libpath:/var/llvm/local-amd64-release-stage2-A-flang-openmp-gcc14-gld/tools/clang/stage2-bins/lib" "/subsystem:console" "-nologo" "-dll" "-implib:a.lib" "-rpath" "/path/to/dir" "/tmp/lit-tmp-s10rro7u/dynamic-linker-074508.o" 
```

https://github.com/llvm/llvm-project/pull/79539