There are a few missing VPX_ prefixes in webpimg.c

[Former user]

I have created a git patch.

so you should be able to apply it to the file in the 2.1.1 tag.

this is the version used in homebrew on osx to build gd.

[Mike Frysinger]

the bitbucket repo is closed. please use github: https://github.com/libgd/libgd/

this should already be fixed there