2.15.90.1 build quirks

["Adam Worrall" <abworrall gmail com>]

desktop/gst-plugins-base: needs a LIBDEP for bootstrap/liboil
platform/atk: needs make makesums
mono/mono: needs PATCHFILES trimmed to match files/

These three packages could all benefit from BUILD_ARGS = -j1, they get
confused during make install otherwise:
 mono/gtk-sharp2.0
 desktop/gnome2-user-docs
 desktop/sound-juicer

office/present is still unable to ./configure itself to find libgoffice.

Other than that, and the other tweaks for x86_64, it seems to build
pretty clean.

So thanks :)

- Adam