Don't insert lifetime.end markers between a musttail call and ret

The allocas going out of scope are immediately killed by the return
instruction.

Reviewers: chandlerc

Differential Revision: http://reviews.llvm.org/D3630
Remove unused variable in inliner

We have to iterate over all the calls that were inlined to find out if
any were musttail.

Sink another variable down to where its used.