deskutils/(py-)spice-gtk: Fix build including with gold linker

These ports starting failing on gold linker with messages like:
./.libs/libspice-client-gtk-3.0.so:

error: undefined reference to 'XGetPointerControl'

./.libs/libspice-client-gtk-3.0.so:

error: undefined reference to 'XChangePointerControl'

The problem and fix was already described here:

https://bugs.freedesktop.org/show_bug.cgi?id=97383

Apparently USES=pathfix and USES=autoreconf can't be used together, so
the pkgconfig directory is now passed via MAKE_ARGS

While here, fix py-spice-gtk install error by removing non-installed file
from the pkg-list.

Approved by: just-fix-it