bug#410: Bug modified from CVS checkin

Clarifies: 410

Set CFLAGS_FOR_BUILD to $(build_CFLAGS) in BUILD_ARGS.  This cause libiberty to
built using matching $(build_CC) and $(build_CFLAGS).  binutils does do a bit
of internal BUILDDEPS'ing, but at least it's somewhat sane.

Nadav,

Please update your sources, make super-clean, and try building this package
again on your Red Hat system, "cd utils/binutils; make DESTIMG=singularity".  I
believe that this fix may close the bug, but I cannot test it.