The memory assigned to the local variable 'copy' needs to be freed.

Found using clang's static analyzer - scan-build

Submitted by:	Thomas Rix <trix@juniper.net>
Reviewed by:	ed
Approved by:	sjg (mentor)
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D9663

usr.bin/tset/map.c

@@ -157,6 +157,7 @@ done:	if (port) {
 badmopt:		errx(1, "illegal -m option format: %s", copy);
 		mapp->porttype = strdup(port);
 	}
+	free(copy);
 
 #ifdef MAPDEBUG
 	(void)printf("port: %s\n", mapp->porttype ? mapp->porttype : "ANY");