[Builtins] Do not use tailcall for Thumb1
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