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.

This is a resend of r208912, which was committed accidentally.

Reviewers: chandlerc

Differential Revision: http://reviews.llvm.org/D3792

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208920 91177308-0d34-0410-b5e6-96231b3b80d8