Test if ALE is loaded before defining intelephense

.vimrc

@@ -168,7 +168,7 @@ let s:intelephense_config = {
 \ },
 \}
 
-if &rtp =~ 'ale\(\.git\)\?'
+if exists("*ale#linter#Define")
 " Custom intelephense
   call ale#linter#Define('php', {
   \   'name': 'intelephense-debug',