frei0r-plugins: use ports-gcc on !clang archs

Initialisation of members is valid but only since C++11,
base-g++ does not support that standard.

OK rapha@ (maintainer), kmos@, jca@

multimedia/frei0r-plugins/Makefile

@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.3 2020/03/04 20:00:55 rapha Exp $
+# $OpenBSD: Makefile,v 1.4 2020/03/07 15:09:49 cwen Exp $
 
 COMMENT =	minimalistic plugin API for video effects
 CATEGORIES =	graphics multimedia
@@ -17,6 +17,8 @@ WANTLIB =	${COMPILER_LIBCXX} m cairo
 
 LIB_DEPENDS =	graphics/cairo
 
+COMPILER =	base-clang ports-gcc
+
 MODULES =	devel/cmake
 
 CONFIGURE_ARGS =	-DWITHOUT_OPENCV=ON \