Added flags that should be ignored for compatibility. These flags will display
a warning. Revision for this patch is here: http://reviews.llvm.org/D4565. This
patch will help with the rebuild of Debian with clang and many other projects
that wish to use clang. Here is a link to the errors that Debian is experiencing:
http://clang.debian.net/status.php?version=3.4.2&key=UNKNOWN_ARG