MIR Parser: Use correct source locations for machine instruction diagnostics.

MIR Parser: Use correct source locations for machine instruction diagnostics.

This commit translates the source locations for MIParser diagnostics from
the locations in the machine instruction string to the locations in the
MIR file.

Reviewers: Duncan P. N. Exon Smith

Differential Revision: http://reviews.llvm.org/D10574

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240474 91177308-0d34-0410-b5e6-96231b3b80d8