Fixes an issue where a signum => name mapping function has multiple case...

Fixes an issue where a signum => name mapping function has multiple case statements that define to the same integral value on my Linux (Ubuntu 12.04, x86_64).  It's for SIGIO and SIGPOLL.
In the case that they are both defined the same.
Patch by Todd Fiala (but typos are mine)

llvm-svn: 197221