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)
(transplanted from 76b1923da63d2e3b8e9010b6138e33f6a99720a8)

diff -durN gcc-4.4.0.orig/libstdc++-v3/include/c_global/cstdio gcc-4.4.0/libstdc++-v3/include/c_global/cstdio

--- gcc-4.4.0.orig/libstdc++-v3/include/c_global/cstdio	2009-04-10 01:23:07.000000000 +0200

+++ gcc-4.4.0/libstdc++-v3/include/c_global/cstdio	2009-05-27 21:38:58.000000000 +0200

@@ -139,7 +139,7 @@

 _GLIBCXX_END_NAMESPACE

-#if _GLIBCXX_USE_C99

+#if _GLIBCXX_USE_C99 || defined __UCLIBC__

 #undef snprintf

 #undef vfscanf