remove parameter names from public headers

inclusion of these names was unintentional and in most cases is a
namespace violation. Daniel Sabogal tracked down and reported these.

include/grp.h

@@ -34,7 +34,7 @@ void           endgrent(void);
 void           setgrent(void);
 
 #ifdef _GNU_SOURCE
-struct group  *fgetgrent(FILE *stream);
+struct group  *fgetgrent(FILE *);
 int putgrent(const struct group *, FILE *);
 #endif