Do not vendor cookbooks using Berkshelf anymore

Instead, use the Berkshelf support in knife-solo and the
vagrant-berkshelf plugin on Vagrant

cookbooks/mingw/files/default/custom-upgrade.sh

@@ -1,23 +0,0 @@
-declare -r CRITICAL_PACKAGES="bash pacman msys2-runtime"
-declare -r OPTIONAL_PACKAGES="msys2-runtime-devel"
-
-# set pacman command if not already defined
-PACMAN=${PACMAN:-pacman}
-# save full path to command as PATH may change when sourcing /etc/profile
-PACMAN_PATH=$(type -P $PACMAN)
-
-run_pacman() {
-	local cmd
-	cmd=("$PACMAN_PATH" "$@")
-	"${cmd[@]}"
-}
-
-if ! run_pacman -Sy; then
-  exit 1
-fi
-
-run_pacman -Qu ${CRITICAL_PACKAGES}
-
-if ! run_pacman -S --noconfirm --needed ${CRITICAL_PACKAGES} ${OPTIONAL_PACKAGES}; then
-  exit 1
-fi