[TSan][MIPS] Adding support for MIPS64

Patch by Sagar Thakur

Reviewers: dvyukov, samsonov, petarj, kcc, dsanders.

Subscribers:  mohit.bhakkad, Anand.Takale, llvm-commits.

Differential Revision: http://reviews.llvm.org/D6291

llvm-svn: 229972