[ARM] Add the option to directly access TLS pointer

This patch enables choice for accessing thread local
storage pointer (like '-mtp' in gcc).

Differential Revision: https://reviews.llvm.org/D34408


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@309381 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed