vchoi_fork

[svn-r22879] Bug Fix: HDFFV 8017
dt_arith would fail in Lion and Mountain Lion system when GCC version 4.2.1
is used with --enable-production. Somehow the -O optimization will fail some of
the hard conversion code.

Solution:
This is just a temporary patch by detecting if this is a Lion or Mountain Lion
system using GCC 4.2.1, then just remove the any -O option from the PROD_CFLAGS.
A better fix should be deviced later.

Tested: Duck(lion) and Owl (mountain lion) tested with --enable-production.
Also tested in Fred and Tejeda, both Snow Leopard systems to verify there is
no undesired side effect.