getopt.h is a GNU-getopt-specific header. always expose GNU functions.

include/getopt.h

@@ -9,7 +9,6 @@ int getopt(int, char * const [], const char *);
 extern char *optarg;
 extern int optind, opterr, optopt;
 
-#ifdef _GNU_SOURCE
 struct option
 {
 	const char *name;
@@ -24,7 +23,6 @@ int getopt_long_only(int, char *const *, const char *, const struct option *, in
 #define no_argument        0
 #define required_argument  1
 #define optional_argument  2
-#endif
 
 #ifdef __cplusplus
 }