[Sparc] Generate ta 1 for the @llvm.debugtrap intrinsic

Summary: Software trap number one is the trap used for breakpoints
in the Sparc ABI.

Reviewers: jyknight, venkatra

Reviewed By: jyknight

Subscribers: fedor.sergeev, jrtc27, llvm-commits

Differential Revision: https://reviews.llvm.org/D48637

llvm-svn: 337163