When comparing -1 to a group id, cast -1 with gid_t because on some systems

such as sunos4 gid_t is an unsigned short.  This prevented the just-added
non-mapped group test from working on sunos4.

rsync.c

@@ -180,8 +180,8 @@ int set_perms(char *fname,struct file_struct *file,STRUCT_STAT *st,
 	}
 
 	change_uid = am_root && preserve_uid && st->st_uid != file->uid;
-	change_gid = !am_daemon && preserve_gid && file->gid != -1 \
-				&& st->st_gid != file->gid;
+	change_gid = !am_daemon && preserve_gid && file->gid != (gid_t) -1 && \
+				st->st_gid != file->gid;
 	if (change_gid && !am_root) {
 		/* enforce bsd-style group semantics: non-root can only
 		    change to groups that the user is a member of */

uidlist.c

@@ -126,7 +126,7 @@ static gid_t match_gid(gid_t gid)
 	if (am_root)
 		last_out = gid;
 	else
-		last_out = -1;
+		last_out = (gid_t) -1;
 	return last_out;
 }