Disable lifetime-start-on-first-use analysis.

Summary:
Turn off lifetime-start-on-first-use enhancement for the moment
pending a fix for bug 27903.

Bug: 27903

Reviewers: tejohnson, wmi, qcolombet, gbiv

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D20731

llvm-svn: 271003