[compiler-rt] [compiler-rt] Install libc++ and libc++abi in build_symbolizer.sh (PR #123104)

[Alexander Richardson via llvm-commits]

arichardson wrote:

Note: this is untested but should hopefully fix the issue in https://github.com/llvm/llvm-project/pull/115380

https://github.com/llvm/llvm-project/pull/123104