emulators/mednafen: switch to base clang on powerpc64 elfv2

Clang 11 can compile this port successfully.

emulators/mednafen/Makefile

@@ -2,6 +2,7 @@
 
 PORTNAME=	mednafen
 PORTVERSION=	1.24.3
+PORTREVISION=	1
 PORTEPOCH=	1
 CATEGORIES=	emulators games
 MASTER_SITES=	https://mednafen.github.io/releases/files/
@@ -29,7 +30,7 @@ SUB_FILES=	pkg-message
 CONFIGURE_ARGS+=--disable-alsa --disable-alsatest \
 		--with-sdl-prefix=${LOCALBASE}
 
-USES=		cpe gl iconv pkgconfig:build sdl tar:xz
+USES=		compiler:c++11-lib cpe gl iconv pkgconfig:build sdl tar:xz
 CPE_VENDOR=	david_shadoff
 
 OPTIONS_DEFINE=	NLS DOCS JACK
@@ -72,14 +73,6 @@ SMS_CONFIGURE_ENABLE=sms
 SWAN_CONFIGURE_ENABLE=wswan
 VB_CONFIGURE_ENABLE=vb
 
-.include <bsd.port.options.mk>
-
-.if defined(PPC_ABI) && ${PPC_ABI} == ELFv2
-USES+=		compiler:gcc-c++11-lib
-.else
-USES+=		compiler:c++11-lib
-.endif
-
 post-patch:
 	@${REINPLACE_CMD} -e 's|versionsort|alphasort|g' \
 		${WRKSRC}/src/drivers/Joystick_Linux.cpp