Log Message:
giflib: Stop installing a broken libgifutil.

The release of giflib 5.1.9 removed GifQuantizeBuffer from its API as it was
undocumented.  Unfortunately a number of third party programs were relying on
this function, and no longer built without it.

The original attempt to fix this was to build and install the libgifutil.so
library that now contains it, but this was done incorrectly (the SONAME was
broken) and required modifying those third party programs anyway to pull in
libgifutil (see e.g. multimedia/mplayer-share), which feels like completely
missing the point.

It is a lot simpler and less error-prone to simply revert the upstream decision
and put GifQuantizeBuffer back into the main library.  This is the approach
that other upstreams (e.g. Fedora) have taken, and so we now do the same.

Bump PKGREVISION.