Update dependencies, build fixes
- Old SDL2 patch removed
- All dependencies updated to the latest version
- Added
build/
to.gitignore
- Bumped default OSX SDK to
macosx10.13
- Added full sysroot path lookup from SDK name string as using just the name (e.g.
macosx10.13
) asCMAKE_OSX_SYSROOT
/-isysroot
didn't work for me.