Removed various exotic -Wxxx flags in the OpenPGM build to get us to what is actually
required and reasonable; added in -fno-strict-aliasing since OpenPGM generates lots
of warnings about dereferencing typed-punned pointers; removed the OpenPGM extra flags
from libzmq_la_CXXFLAGS and left them only in libzmq_la_CFLAGS so that our code
is not built with the OpenPGM extra flags.