Speed up macOS CI

- skip nonsense during package installation
- use actual number of available cores

util/ci/common.sh

@@ -33,8 +33,11 @@ install_macos_deps() {
 		cmake gettext freetype gmp jpeg-turbo jsoncpp leveldb
 		libogg libpng libvorbis luajit zstd
 	)
-	brew update
-	brew install "${pkgs[@]}"
+	export HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1
+	export HOMEBREW_NO_INSTALL_CLEANUP=1
+	# contrary to how it may look --auto-update makes brew do *less*
+	brew update --auto-update
+	brew install --display-times "${pkgs[@]}"
 	brew unlink $(brew ls --formula)
 	brew link "${pkgs[@]}"
 }