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.
Last updated from upstream on 13/1/22.
./autogen.sh --prefix=/home/john/vips
make
make install
Run:
./update.sh
To clone the upstream libnsgif repo, copy in the source files and apply all patches.
No attempt made to run tests or build docs.