cc/gcc: Make usage of --enable-target-optspace configurable

Optionally configure to compile gcc-internal libs with -Os.

yann.morin.1998@anciens.enib.fr:
Rename the config options, it is in the GCC /namespace/.

 reporter_name="Harold Grovesteen"

 reporter_url="http://sourceware.org/ml/crossgcc/2009-11/msg00052.html"

 reporter_comment=""