temp/gtk+3.0: prevent unexpected downgrade

temp/gtk+3.0: rebase on Alpine's APKBUILD

Use meson instead of autotools and disable building manuals, man pages and tests. This reduces the cross compile time for aarch64 (which had forced -j1 before) from ~80 min to ~17 min (!). Most importantly, it seems to pass every time now (whereas before it would get stuck in ~2 of 3 tries).

Related: https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/main/gtk+3.0/APKBUILD

temp/gtk+3.0: prevent unexpected downgrade

Override the library version, so apk does not downgrade the package if Alpine's package has a higher library version:

$ sudo apk upgrade
...
(15/80) Downgrading gtk+3.0 (9999_git20191223-r0 -> 3.24.22-r0)
...

Fixes #694 (closed)