wxWidget was using jpeg and png in its building script
remove .already_build from wxWidget, and rebuild libraries
--with-png:builtin for --with-libpng=builtin
Minor point: were spaces added before CONF_OPTS?
Otherwise it looks good.
Successful build - Chance fights ever on the side of the prudent.
Link to build: https://jenkins.wildfiregames.com/job/docker-differential/28/display/redirect
Link to build: https://jenkins.wildfiregames.com/job/docker-differential/29/display/redirect
Fixed in rP22454.