Add discriminators for call instructions that are from the same line and same basic block.

Summary: Call instructions that are from the same line and same basic block needs to have separate discriminators to distinguish between different callsites.

Reviewers: davidxl, dnovillo, dblaikie

Subscribers: dblaikie, probinson, llvm-commits

Differential Revision: http://reviews.llvm.org/D14464

llvm-svn: 252492