core: no need for defaulting support checks. just check if supports and key are set.

Author: ctalkington

lib/core.js

@@ -151,9 +151,9 @@ Archiver.prototype._modulePipe = function() {
 };
 
 Archiver.prototype._moduleSupports = function(key) {
-  this._module.supports = util.defaults(this._module.supports, {
-    directory: false
-  });
+  if (!this._module.supports || !this._module.supports[key]) {
+    return false;
+  }
 
   return this._module.supports[key];
 };