Fixing a corner-case bug in strchr and strrchr lib call optimizations where
the input character is not converted to char before comparing with zero.

The patch was discussed in this thread:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20130812/184069.html



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188489 91177308-0d34-0410-b5e6-96231b3b80d8