IR: Replace the "Linker Options" module flag with "llvm.linker.options" named metadata.

The new metadata is easier to manipulate than module flags.

Differential Revision: https://reviews.llvm.org/D31349

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305227 91177308-0d34-0410-b5e6-96231b3b80d8
18 files changed