[compiler-rt] Make add_custom_libcxx() resilient to DESTDIR being set#115525

arichardson merged 2 commits intomainllvm/llvm-project:mainfrom

users/arichardson/spr/compiler-rt-make-add_custom_libcxx-resilient-to-destdir-being-setllvm/llvm-project:users/arichardson/spr/compiler-rt-make-add_custom_libcxx-resilient-to-destdir-being-setCopy head branch name to clipboard