[Sparc] Use the names .rem and .urem instead of __modsi3 and __umodsi3

Summary: These are the names used in libgcc.

Reviewers: venkatra, jyknight, ekedaigle

Reviewed By: jyknight

Subscribers: joerg, fedor.sergeev, jrtc27, llvm-commits

Differential Revision: https://reviews.llvm.org/D48915

llvm-svn: 337164