libtool already produces a table of contents, and ranlib just gives
spurious errors because it doesn't understand universal binaries.
Reviewed By: phosek
Differential Revision: https://reviews.llvm.org/D86365
compiler-rt already uses libtool instead of ar when building for
Apple platform, but that's not being used when builtins are being
built separately e.g. as part of the runtimes build. This change
extracts the logic setting up libtool into a separate file and uses
it from both the compiler-rt and standalone builtins build.
Differential Revision: https://reviews.llvm.org/D62820
llvm-svn: 362466
Shoaib Meenai