[libc-eglibc] Rewrite part of the code

Rewrite part of the code to better match the rest.
Most notably, rewrite handling of:
if [ ... ] && [ ... ]
to:
if [ ... -a ... ]

This has the positive side effect of calling "[" only once, although
"[" is probably a shell built-in.

 #!/bin/sh

 # Needed for systems without gettext

 $* -xc -o /dev/null - > /dev/null 2>&1 << EOF

 #include <libintl.h>

 int main()

 {

 	gettext("");

 	return 0;

 }

 EOF

 if [ ! "$?" -eq "0"  ]; then

 	echo -DKBUILD_NO_NLS;

 fi