pixman: enable hybrid builds.

x11-libs/pixman/pixman-0.20.0.recipe

@@ -16,6 +16,11 @@ COPYRIGHT="1987-1998  The Open Group
 REVISION="1"
 
 ARCHITECTURES="x86 x86_64"
+if [ $effectiveTargetArchitecture != x86_gcc2 ]; then
+	# x86_gcc2 is fine as primary target architecture as long as we're building
+	# for a different secondary architecture.
+	ARCHITECTURES="$ARCHITECTURES x86_gcc2"
+fi
 SECONDARY_ARCHITECTURES="x86"
 
 PROVIDES="