Switch to ports-gcc on sparc64 so these ports compile.

OK sthen@ tb@

graphics/decker/Makefile

@@ -13,6 +13,10 @@ PERMIT_PACKAGE =	Yes
 
 WANTLIB +=		SDL2 SDL2_image c m
 
+# needs -Wpedantic and other -W flags
+COMPILER =		base-clang ports-gcc
+COMPILER_LANGS =	c
+
 USE_GMAKE =		Yes
 
 BUILD_DEPENDS =		editors/vim \

graphics/libsixel/Makefile

@@ -12,6 +12,10 @@ HOMEPAGE =	https://github.com/saitoha/libsixel
 # MIT
 PERMIT_PACKAGE =	Yes
 
+# needs thread local storage
+COMPILER =	base-clang ports-gcc
+COMPILER_LANGS=	c
+
 WANTLIB +=	c jpeg m png z
 
 SITES =		https://github.com/saitoha/libsixel/releases/download/v$V/

graphics/ruby-rmagick/Makefile

@@ -9,6 +9,9 @@ HOMEPAGE =	https://github.com/rmagick/rmagick
 # MIT
 PERMIT_PACKAGE = Yes
 
+# needs -std=c++11
+COMPILER =	base-clang ports-gcc
+
 MODULES =	lang/ruby
 
 WANTLIB += MagickCore-6.Q16 MagickWand-6.Q16