Migrate to autoconf 2.69 for arm 64 support
I've got a bug report , that gd contains config.guess and config.sub, which don't support arm 64 (aarch64). The support was added in autoconf 2.69.
I'm unfortunately not able to confirm this bug, because I don't have an access to ARM 64 machine currently.
Would it be possible to migrate these scripts to newer version to be able to build gd on arm 64 smoothly?