games/yquake2: enable macppc

Tested and found out it builds and runs fine on macppc.

ok to enable it there?

Index: Makefile
===================================================================
RCS file: /cvs/ports/games/yquake2/Makefile,v
retrieving revision 1.28
diff -u -p -r1.28 Makefile
--- Makefile 26 Sep 2023 09:41:45 -0000 1.28
+++ Makefile 6 Feb 2024 01:17:26 -0000
@@ -1,4 +1,4 @@
-ONLY_FOR_ARCHS= i386 amd64 sparc64
+ONLY_FOR_ARCHS= i386 amd64 sparc64 macppc

COMMENT= Yamagi Quake II
N= yquake2