Besides all the goodness from modularizing a header, this is necessary
to compile ToT with modules with the clang host compiler from Xcode 9 in
macOS 10.13, which our bots don't use yet.
rdar://problem/35038151
llvm-svn: 316414
A client of a header that relies on ABI breaking should get the macro
exported there.
Before this, the unittest for Support/Error including Support/Error.h
didn't get the macro exported by the Support module, because the
latter only re-export its submodules and included module, not
textual headers.
Hopefully, it'll also fix the build with local submodule visibility,
since the LLVM_Utils contains two submodules: ADT and Support. They
both include abi-breaking.h that defines a symbol. The textual
inclusion lead to a double definition of the symbol which broke
the parent module.
Differential Revision: https://reviews.llvm.org/D27273
llvm-svn: 288400
