[libc++abi][ci] Add a from-scratch config for libc++abi on Apple/system
I came across an issue where since we build the library for Apple with
the install name directory being /usr/lib, which means that if we don't
run the tests with DYLD_LIBRARY_PATH, we'll end up loading the
system-provided libc++abi when running the tests. That wreaks havoc.
Instead of fixing it in the legacy config file, this commit introduces
an Apple libc++abi config file that does the right thing.
Differential Revision: https://reviews.llvm.org/D111279
2 files changed