Its not computed properly during configure and
we configure uclibc with widechar support anyway
so its fine to cache it. It fixes the errors like
| In file included from ./stdio.h:31:0,
| from fpurge.h:20,
| from fpurge.c:20:
| /home/kraj/work/angstrom/sources/openembedded-core/build/tmp-uclibc/sysroots/qemux86/usr/include/stdio.h:662:40: error: expected declaration specifiers or '...' before '(' token
| make[4]: *** [fpurge.o] Error 1
