[lld/mac] For catalyst outputs, tolerate implicitly linking against mac-only tbd files

Before this,

  clang empty.cc -target x86_64-apple-ios13.1-macabi \
      -framework CoreServices -fuse-ld=lld

would error out with

    ld64.lld: error: path/to/MacOSX.sdk/System/Library/Frameworks/
         CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/
         Versions/A/CarbonCore.tbd(
             /System/Library/Frameworks/
             CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/
             Versions/A/CarbonCore) is incompatible with x86_64 (macCatalyst)

Now it works, like with ld64.

Differential Revision: https://reviews.llvm.org/D124336