[Builtins] Do not use tailcall for Thumb1

Summary:
The `b` instruction in Thumb1 has limited range, which may cause link-time errors if the jump target is far away.
This patch guards the tailcalls for non-Thumb1

Reviewers: peter.smith, compnerd, rengolin, eli.friedman

Reviewed By: rengolin

Subscribers: joerg, dalias, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D39700

llvm-svn: 317814