Libpgm is from OpenPGM, An implementation of the PGM reliable
multicast protocol. It's a dep for zeromq that fixes zeromq
so that it compiles on ML. Tested with clang and llvm from
XCode-4.4.1.
FixesHomebrew/homebrew#14210ClosesHomebrew/homebrew#14290.
Signed-off-by: Adam Vandenberg <flangy@gmail.com>
