Fix style of the libgen.h header.

- Remove unneeded declarations of removed/unimplemented features.
- Add missing tab after #define.
- Add missing ! before trailing comment.

include/libgen.h

@@ -29,22 +29,14 @@
  */
 
 #ifndef _LIBGEN_H_
-#define _LIBGEN_H_
+#define	_LIBGEN_H_
 
 #include <sys/cdefs.h>
 
 __BEGIN_DECLS
-
 char	*basename(const char *);
 char	*basename_r(const char *, char *);
 char	*dirname(const char *);
-#if 0
-char	*regcmp(const char *, ...);
-char	*regex(const char *, const char *, ...);
-
-extern char *__loc1;
-#endif
-
 __END_DECLS
 
-#endif /* _LIBGEN_H_ */
+#endif /* !_LIBGEN_H_ */