cc/gcc: fix building for powerpc for the 4.4.x series

Reported by: Thomas Petazzoni
http://sourceware.org/ml/crossgcc/2010-03/msg00057.html

Discussions:
http://lists.uclibc.org/pipermail/uclibc/2010-March/043697.html
http://lists.uclibc.org/pipermail/buildroot/2010-March/032790.html
http://ibot.rikers.org/%23uclibc/20100316.html.gz
(search for "copysignl", by kos_tom, blindvt and y_morin)

 reporter_name="Yann E. MORIN"

 reporter_url="http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool"

 reporter_comment=""