meson: Add subproject fallbacks for most dependencies
glib, fribidi, harfbuzz, fontconfig, freetype, cairo
- small fixes when building as a subproject
Only fribidi and glib have been added as wraps because the rest are not upstream yet (need more testing) and can be found at:
https://github.com/centricular/harfbuzz
https://github.com/centricular/fontconfig
https://github.com/centricular/cairo
https://github.com/centricular/freetype2
I can add them as wraps anyway if pointing to third-party repos is ok.
This is needed for gtk!232 (merged).