[compiler-rt] [compiler-rt] Use installed libc++(abi) for tests instead of build tree (PR #115077)

[Alexander Richardson via llvm-commits]

arichardson wrote:

I just looked at the generated build.ninja and there is definitely a dependency from 
`compiler-rt/lib/fuzzer/CMakeFiles/RTfuzzer.x86_64.dir/FuzzerExtraCountersWindows.cpp.o` to `compiler-rt/lib/fuzzer/libcxx_fuzzer_x86_64-install`

https://github.com/llvm/llvm-project/pull/115077