[rtsan] Explicitly link pthread in the tests and dynamic libraries (#…

…98256)

Follow up to #98219

This reverts commit
[14f7450](14f7450)

Ensure that -pthread is explicitly linked when running the rtsan tests. 

Issue this fixes:
```
FAILED: compiler-rt/lib/rtsan/tests/Rtsan-powerpc64le-NoInstTest /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests/Rtsan-powerpc64le-NoInstTest 
cd /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests && /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/./bin/clang++ RtsanNoInstTestObjects.rtsan_preinit.cpp.powerpc64le.o RtsanNoInstTestObjects.rtsan_test_context.cpp.powerpc64le.o RtsanNoInstTestObjects.rtsan_test_main.cpp.powerpc64le.o RtsanNoInstTestObjects.gtest-all.cc.powerpc64le.o RtsanNoInstTestObjects.gmock-all.cc.powerpc64le.o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests/libRTRtsanTest.powerpc64le.a -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/runtimes/runtimes-bins/compiler-rt/lib/rtsan/tests/./Rtsan-powerpc64le-NoInstTest -Wthread-safety -Wthread-safety-reference -Wthread-safety-beta -resource-dir=/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/./lib/../lib/clang/19 -Wl,-rpath,/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/./lib/../lib/clang/19/lib/powerpc64le-unknown-linux-gnu -lstdc++ -no-pie -latomic -m64 -fno-function-sections
/usr/bin/ld: RtsanNoInstTestObjects.gtest-all.cc.powerpc64le.o: undefined reference to symbol 'pthread_getspecific@@GLIBC_2.17'
//usr/lib64/libpthread.so.0: error adding symbols: DSO missing from command line
```

compiler-rt/cmake/Modules/AllSupportedArchDefs.cmake

@@ -32,9 +32,9 @@ set(ALL_ASAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${RISCV64}
     ${LOONGARCH64})
 set(ALL_ASAN_ABI_SUPPORTED_ARCH ${X86_64} ${ARM64} ${ARM64_32})
 set(ALL_DFSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${LOONGARCH64})
-#set(ALL_RTSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${RISCV64}
-#    ${MIPS32} ${MIPS64} ${PPC64} ${S390X} ${SPARC} ${SPARCV9} ${HEXAGON}
-#    ${LOONGARCH64})
+set(ALL_RTSAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${RISCV64}
+    ${MIPS32} ${MIPS64} ${PPC64} ${S390X} ${SPARC} ${SPARCV9} ${HEXAGON}
+    ${LOONGARCH64})
 
 if(ANDROID)
   set(OS_NAME "Android")

compiler-rt/lib/rtsan/tests/CMakeLists.txt

@@ -36,6 +36,8 @@ set(RTSAN_UNITTEST_LINK_FLAGS
   ${SANITIZER_TEST_CXX_LIBRARIES}
   -no-pie)
 
+append_list_if(COMPILER_RT_HAS_LIBPTHREAD -pthread RTSAN_UNITTEST_LINK_FLAGS)
+
 if (APPLE)
   add_weak_symbols("sanitizer_common" WEAK_SYMBOL_LINK_FLAGS)
   list(APPEND RTSAN_UNITTEST_LINK_FLAGS ${WEAK_SYMBOL_LINK_FLAGS})