First the least significant: is there a reason why gdk-pixbuf plugin is disabled ? I don't know about its usability, but the comment in the ebuild is wrong - it's for gdk-pixbuf:2. USE=gs doesn't seem to be implemented correctly - it should be $(use_with ghostscript)... and it it were, perhaps somebody would have noticed "-X gs" failure. Honestly, it comes down to lefty needing a separate useflag (as proposed in bug 372939), cause right now --without-x disables ghostscript (there seems to be a typo in AM_CONDITIONAL for XRENDER too).
Created attachment 315663 [details, diff] ebuild patch?
Comment on attachment 315663 [details, diff] ebuild patch? uncomplete
It should be 'use_with', not 'use_enable'. Also, back in bug 372939 I've already mentioned, that due to quirks of the build system, lefty could use a separate useflag (and back then I've failed to notice that typo in AM_CONDITIONAL for XRENDER).
I think I have adapted the 2.38.0-r1 ebuild to most of the changes you suggest... also, it looks like "-X postscript" still builds for me (if something is still valid maybe a fresh bug report with that latest ebuild would be easier to review and commit)
