Allow our own cabal-install bindist builds

.github/scripts/brew.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+set -eux
+
+# shellcheck disable=SC1091
+. .github/scripts/env.sh
+
+if [ -e "$HOME/.brew" ] ; then
+	(
+	cd "$HOME/.brew"
+	git fetch --depth 1
+	git reset --hard origin/master
+	)
+else
+	git clone --depth=1 https://github.com/Homebrew/brew "$HOME/.brew"
+fi
+export PATH="$HOME/.brew/bin:$HOME/.brew/sbin:$PATH"
+
+mkdir -p "$CI_PROJECT_DIR/.brew_cache"
+export HOMEBREW_CACHE="$CI_PROJECT_DIR/.brew_cache"
+mkdir -p "$CI_PROJECT_DIR/.brew_logs"
+export HOMEBREW_LOGS="$CI_PROJECT_DIR/.brew_logs"
+mkdir -p /private/tmp/.brew_tmp
+export HOMEBREW_TEMP=/private/tmp/.brew_tmp
+
+#brew update
+brew install ${1+"$@"}
+