nss: Remove <gnu/lib-names.h> include from nsswitch.c

nsswitch.c no longer references any of the *_SO macros provided by
<gnu/lib-names.h>. The only consumer, __nss_shlib_revision, moved to
nss_module.c as part of the NSS reorganization in glibc 2.33 (and
nss_module.c includes the header unconditionally), but the guarded
include was left behind.

Signed-off-by: Michael Ford <fanquake@gmail.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

nss/nsswitch.c

@@ -33,10 +33,6 @@
 #include <shadow.h>
 #include <unistd.h>
 
-#if !defined DO_STATIC_NSS || defined SHARED
-# include <gnu/lib-names.h>
-#endif
-
 #include "nsswitch.h"
 #include "../nscd/nscd_proto.h"
 #include <sysdep.h>