Make return code in noarg case GNU-compatible

lib/libc/stdlib/getopt_long.3

@@ -311,26 +311,26 @@ This practice is wrong, and should not be used in any current development.
 .\" to
 .\" mean the preceding option takes an optional argument.
 .\" .El
-.It
-Return value in case of missing argument if first character
-(after
-.Ql +
-or
-.Ql - )
-in option string is not
-.Ql \&: :
-.Bl -tag -width ".Bx"
-.It Tn GNU
-returns
-.Ql \&?
-.It Bx
-returns
-.Ql \&:
-(since
-.Bx Ns 's
-.Fn getopt
-does).
-.El
+.\" .It
+.\" Return value in case of missing argument if first character
+.\" (after
+.\" .Ql +
+.\" or
+.\" .Ql - )
+.\" in option string is not
+.\" .Ql \&: :
+.\" .Bl -tag -width ".Bx"
+.\" .It Tn GNU
+.\" returns
+.\" .Ql \&?
+.\" .It Bx
+.\" returns
+.\" .Ql \&:
+.\" (since
+.\" .Bx Ns 's
+.\" .Fn getopt
+.\" does).
+.\" .El
 .\" .It
 .\" Handling of
 .\" .Ql --a

lib/libc/stdlib/getopt_long.c

@@ -284,7 +284,11 @@ parse_long_options(char * const *nargv, const char *options,
 				optopt = long_options[match].val;
 			else
 				optopt = 0;
+#ifdef GNU_COMPATIBLE
+			return (BADCH);
+#else
 			return (BADARG);
+#endif
 		}
 		if (long_options[match].has_arg == required_argument ||
 		    long_options[match].has_arg == optional_argument) {