libc/glibc: configure libc headers with support for 128-bit long double

At the headers install pass, there's no compiler to test for the size
of long double. Help it: we know that the compiler does support 128-bit
long double, in the IBM extended precision.

Kindly pointed out, and explained, by Mike FRYSINGER:
http://sourceware.org/ml/crossgcc/2009-11/msg00040.html
http://sourceware.org/ml/crossgcc/2009-11/msg00057.html

#!/bin/sh

SKIP_ME="### CT_NG SKIP ME ###"

skip_me=$(($(cat "${0}" |@@grep@@ --binary-files=text -o -b -E "^${SKIP_ME}$" |cut -d : -f 1)+${#SKIP_ME}+1))

dd if="${0}" bs=${skip_me} skip=1 2>/dev/null |bzcat

exit 0

### CT_NG SKIP ME ###