Implement a FIXME by checking to make sure that a malloc is not being used

Implement a FIXME by checking to make sure that a malloc is not being used
in scary and unknown ways before we promote it.  This fixes the miscompilation
of 188.ammp that has been plauging us since a globalopt patch went in.

Thanks a ton to Tanya for helping me diagnose the problem!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18418 91177308-0d34-0410-b5e6-96231b3b80d8