Bug 457753: Ensure that the directory exists before zipping up crashreporter symbols. r=ted

Makefile.in

@@ -196,6 +196,7 @@ ifdef MOZ_CRASHREPORTER
 	  $(MAKE_SYM_STORE_PATH) >                                        \
 	  $(DIST)/crashreporter-symbols/$(SYMBOL_INDEX_NAME)
 	echo packing symbols
+	$(NSINSTALL) -D $(DIST)/$(PKG_PATH)
 	cd $(DIST)/crashreporter-symbols && \
           zip -r9D "../$(PKG_PATH)$(SYMBOL_ARCHIVE_BASENAME).zip" .
 endif # MOZ_CRASHREPORTER