Complete upgrade of gcc 4.7.3 => 4.7.4

Complete upgrade of gcc 4.7.3 => 4.7.4

The GCC Bugzilla shows 134 PRs were resolved on the GCC 4.7 branch since
GCC 4.7.3 was released.  I've run into one c++ bug on ports involving
try-catch that should be fixed (the current solution is use GCC 4.8.3
from ports).  Not all the PRs listed in milestone 4.7.4 are pertinent
for DragonFly's base compiler though.