libnsgif-autotools

This is libnsgif, but with an autotools build system. The original libnsgif uses the netsurf build system and is a little awkward to make in isolation, or from jhbuild.

Based on libnsgif-0.2.1, with two patches:

1. prevent it modifying the input buffer on error

2. fix PREVIOUS handling, see http://source.netsurf-browser.org/libnsgif.git/commit/?id=8442a27c2bb8df48029ceea6e64c4930106a57fc

To build

./autogen.sh --prefix=/home/john/vips
make
make install

To update

When netsurf release a new version:

• copy in sources
• except for libnsgif.pc.in, it needs modifying for autotools
• reapply any patches from git, eg. no input modification

To do

No attempt made to run tests or build docs.