[5.8] LLVM product: amend installation path of compiler-rt libraries...

[edymtt]

...copied from the host toolchain

Addresses #62626, rdar://104724130

(cherry picked from commit a2aed1f, #63311 )

[edymtt]

@swift-ci please test

[edymtt]

@swift-ci please build toolchain

[edymtt]

Verified with manual inspection that the compiler-rt libraries for iOS/tvOS/watchOS (and matching simulator) are present in the generate toolchain

> ls -1 Library/Developer/Toolchains/swift-PR-63312-526.xctoolchain/usr/lib/clang/13.0.0/lib/darwin/
.
..
libclang_rt.asan_osx_dynamic.dylib
libclang_rt.cc_kext.a
libclang_rt.fuzzer_interceptors_osx.a
libclang_rt.fuzzer_no_main_osx.a
libclang_rt.fuzzer_osx.a
libclang_rt.ios.a
libclang_rt.iossim.a
libclang_rt.lsan_osx_dynamic.dylib
libclang_rt.orc_osx.a
libclang_rt.osx.a
libclang_rt.profile_osx.a
libclang_rt.stats_client_osx.a
libclang_rt.stats_osx_dynamic.dylib
libclang_rt.tsan_osx_dynamic.dylib
libclang_rt.tvos.a
libclang_rt.tvossim.a
libclang_rt.ubsan_minimal_osx.a
libclang_rt.ubsan_minimal_osx_dynamic.dylib
libclang_rt.ubsan_osx.a
libclang_rt.ubsan_osx_dynamic.dylib
libclang_rt.watchos.a
libclang_rt.watchossim.a
libclang_rt.xray-basic_osx.a
libclang_rt.xray-fdr_osx.a
libclang_rt.xray-profiling_osx.a
libclang_rt.xray_osx.a