tsan: enable sse4.2 in tests

[dvyukov]

Summary

Pass -msse4.2 flag to the tests the same way we do for the runtime.
Layout of some structs in the runtime headers depends on the flag
(TSAN_VECTORIZE), so we need it to be consistent across the runtime
and tests.

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

 )
 
 if(COMPILER_RT_TSAN_DEBUG_OUTPUT)
   # Need to match these flags with the runtime.
   list(APPEND TSAN_UNITTEST_CFLAGS -DTSAN_COLLECT_STATS=1
                                    -DTSAN_DEBUG_OUTPUT=2)
 endif()
 
+append_list_if(COMPILER_RT_HAS_MSSE4_2_FLAG -msse4.2 TSAN_UNITTEST_CFLAGS)
+
 set(TSAN_TEST_ARCH ${TSAN_SUPPORTED_ARCH})
 
 set(LINK_FLAGS ${COMPILER_RT_UNITTEST_LINK_FLAGS})
 foreach(lib ${SANITIZER_TEST_CXX_LIBRARIES})
   list(APPEND LINK_FLAGS -l${lib})
 endforeach()
 
 if(APPLE)