buildlink confusion if both quartz and x11 are set

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

On Mac OS X, I'm building with PKG_DEFAULT_OPTIONS including quartz.

This seems to lead to some buildlink3 confusion for packages that also 
have a x11 options, causing both quartz and x11 being set.

Building cairomm fails with
	===> Creating toolchain wrappers for cairomm-1.12.2
	pkg_info: can't find package `_BLNK_PKG_DBDIR.MesaLib_not_found'
	ERROR: fontconfig>=2.10.93 fontconfig>=2.1nb2 is not installed; can't buildlink files.
unless building cairo with -x11.

Building inkscape fails with
	===> Creating toolchain wrappers for inkscape-0.92.1nb1
	pkg_info: can't find package `_BLNK_PKG_DBDIR.libXft_not_found'
	ERROR: fontconfig>=2.10.93 fontconfig>=2.1nb2 is not installed; can't buildlink files.
probably because pango has both quartz an x11 set.

I'm not sure what the root cause for this is.

jperkin@, what options are you performing your OSX bulk builds with?