[CFI] Remove LinkerSubsectionsViaSymbols.

Since D17854 LinkerSubsectionsViaSymbols is unnecessary.

It is interfering with ThinLTO implementation of CFI-ICall, where
the aliases used on the !LinkerSubsectionsViaSymbols branch are
needed to export jump tables to ThinLTO backends.

This is the second attempt to land this change after fixing PR33316.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305031 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed