Created attachment 449868 [details] build.log I'm getting header mismatch errors on both 1.14.4 and 1.14.6, I've not tried lower versions. ABI="64" had installed in the past. I tried to install gnome-base/librsvg but it's a chicken, egg, scenario with cairo.
Check how exactly the headers in question differ - going by the ebuild, DirectFB should already be covered... If it does come down to librsvg, you might need need some temporary useflag changes, but that will effectively invalidate this problem as a bug.
Can you confirm that disabling USE=directfb avoids the problem?
I can confirm disabling directfb allows it to build.
Is that something you actually need? directfb is package.use.mask'd on cairo, so you went out of your way to enable it. It's package.use.mask'd exactly for this reason -- because dev-libs/DirectFB isn't ported to multilib. It's not something I'm excited about supporting. I don't have any use for it. I'm not sure what it's good for these days...
Well, development for directfb is back [1], so there's that. [1] http://www.directfb.net/