config.h: fix uclibc build without NLS

[ffontaine]

uclibc defines __GLIBC__ but doesn't always have NLS support resulting in the following build failure:

In file included from whois.h:1,
                 from whois.c:44:
utils.h:38:11: fatal error: libintl.h: No such file or directory
   38 | # include <libintl.h>
      |           ^~~~~~~~~~~

Fixes:

• http://autobuild.buildroot.org/results/a9d1c9076345d94ac2f9a4008b8563c5a34f655e

Signed-off-by: Fabrice Fontaine [email protected]