simplify part of getopt_long

as a result of commit e8e4e56a8c,
the later code path for setting optarg to a null pointer is no longer
necessary, and removing it eliminates an indention level and arguably
makes the code more readable.

src/misc/getopt_long.c

@@ -87,8 +87,7 @@ static int __getopt_long_core(int argc, char *const *argv, const char *optstring
 					return '?';
 				}
 				optarg = opt+1;
-			} else {
-				if (longopts[i].has_arg == required_argument) {
+			} else if (longopts[i].has_arg == required_argument) {
 				if (!(optarg = argv[optind])) {
 					if (colon) return ':';
 					if (!opterr) return '?';
@@ -99,7 +98,6 @@ static int __getopt_long_core(int argc, char *const *argv, const char *optstring
 					return '?';
 				}
 				optind++;
-				} else optarg = NULL;
 			}
 			if (idx) *idx = i;
 			if (longopts[i].flag) {