[LLDB][MIPS] Fix TestInferiorAssert.py for MIPS

Patch by Nitesh Jain.

Summary: The debug version of libc.so is require for backtracing which may not be available on all platforms.

Reviewers: ovyalov, clayborg
Subscribers: zturner, lldb-commits, mohit.bhakkad, sagar, bhushan, jaydeep
Differential: http://reviews.llvm.org/D17131
llvm-svn: 262011