Travis: Use Xcode 12.2 for all iOS & macOS builds
There doesn't seem to be any performance or compatibility downside to
this, and it has the advantages of simplicity and consistency between
the PR and official builds.
diff --git a/.travis.yml b/.travis.yml
index 5f6a51f..9d135db 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -77,7 +77,6 @@
rm MacPorts-2.6.4-10.15-Catalina.pkg &&
sudo /opt/local/bin/port -N install yasm md5sha1sum &&
export PATH=/opt/local/bin:$PATH &&
- ln -fs /Applications/Xcode.app /Applications/Xcode83.app;
ln -fs /Applications/Xcode.app /Applications/Xcode122.app;
fi
- if [ "${BUILD_OFFICIAL:-}" != "" ]; then