It doesn't warn if the integer is known at compile time and within
the bounds of the string.

Discussion: http://comments.gmane.org/gmane.comp.compilers.clang.scm/47203



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151943 91177308-0d34-0410-b5e6-96231b3b80d8