audit: check for DB deps too

Library/Homebrew/cmd/audit.rb

@@ -265,7 +265,7 @@ def audit_formula_instance f
     end
 
     case d
-    when "git", "python", "ruby", "emacs"
+    when "git", "python", "ruby", "emacs", "mysql", "postgresql"
       problems << " * Don't use #{d} as a dependency; we allow non-Homebrew #{d} installs."
     end
   end