[sparc64] Fix build of games/yquake2

Switch COMPILER to base-clang ports-gcc to allow build. yquake2 uses CFLAGS
unavailable to base-gcc.

ok?

--Kurt

Index: Makefile
===================================================================
RCS file: /cvs/ports/games/yquake2/Makefile,v
retrieving revision 1.24
diff -u -p -r1.24 Makefile
--- Makefile 15 Dec 2021 13:44:11 -0000 1.24
+++ Makefile 5 Jan 2022 06:52:40 -0000
@@ -17,6 +17,9 @@ EXTRACT_SUFX= .tar.xz
# GPLv2
PERMIT_PACKAGE= Yes

+COMPILER= base-clang ports-gcc
+COMPILER_LANGS= c
+
WANTLIB += GL SDL2 c curl execinfo m openal

# Libraries loaded with dlopen(3)