Cache Clojure git dependencies

The [Clojure CLI tools][clojure-cli] have a mechanism of downloading
dependencies directly from git repositories rather than from a package
manager. This patch caches the directory which stores these downloads,
speeding up builds of repos that use these types of dependencies.

[clojure-cli]: https://clojure.org/guides/deps_and_cli

run-build-functions.sh

@@ -591,6 +591,7 @@ install_dependencies() {
   if [ -f deps.edn ]
   then
     restore_home_cache ".m2" "maven dependencies"
+    restore_home_cache ".gitlibs" "clojure git dependencies"
     restore_cwd_cache ".cpcache" "clojure classpath"
     echo "Installing Clojure dependencies"
     if clojure -Spath -Sforce >/dev/null
@@ -747,6 +748,7 @@ cache_artifacts() {
   cache_home_directory ".emacs.d" "emacs cache"
   cache_home_directory ".m2" "maven dependencies"
   cache_home_directory ".boot" "boot dependencies"
+  cache_home_directory ".gitlibs" "clojure git dependencies"
   cache_home_directory ".composer" "composer dependencies"
   cache_home_directory ".homebrew-cache", "homebrew cache"
   cache_home_directory ".rustup" "rust rustup cache"