Only execute chmod exporting iOS when on Mac OS X

platform/iphone/export/export.cpp

@@ -260,10 +260,12 @@ Error EditorExportPlatformIOS::export_project(const Ref<EditorExportPreset> &p_p
 			f->close();
 			memdelete(f);
 
+#ifdef OSX_ENABLED
 			if (is_execute) {
 				// we need execute rights on this file
 				chmod(file.utf8().get_data(), 0755);
 			}
+#endif
 		}
 
 		ret = unzGoToNextFile(src_pkg_zip);