docs: Add compiler and toolchain requirements from the wiki
These files are Markdown-ified versions of the following wiki pages:
- https://wiki.gnome.org/Projects/GLib/CompilerRequirements
- https://wiki.gnome.org/Projects/GLib/SupportedPlatforms
Keeping the files in version control with the rest of the documentation means they should be easier to find, and easier to remember to keep up to date.
They have not been modified other than to change to Markdown and tweak the formatting. Content updates to them will be done in future commits.
Signed-off-by: Philip Withnall pwithnall@endlessos.org
Edited by Philip Withnall