[sparc64] Fix build of graphics/mojoshader

graphics/mojoshader needs ports-gcc on sparc64.

ok?

(cc MAINTAINER)

--Kurt

Index: Makefile
===================================================================
RCS file: /cvs/ports/graphics/mojoshader/Makefile,v
retrieving revision 1.12
diff -u -p -r1.12 Makefile
--- Makefile 12 Dec 2021 04:41:03 -0000 1.12
+++ Makefile 5 Jan 2022 07:21:08 -0000
@@ -18,6 +18,9 @@ HOMEPAGE = https://icculus.org/mojoshade
# zlib
PERMIT_PACKAGE = Yes

+COMPILER = base-clang ports-gcc
+COMPILER_LANGS = c
+
WANTLIB += m

MODULES = devel/cmake