[tests] Include 'long_test' in check-swift-all-* test targets

Author: rintaro

test/lit.cfg

@@ -471,6 +471,7 @@ else:
 swift_run_only_tests = lit_config.params.get('run_only_tests', 'all_except_long')
 if swift_run_only_tests == 'all':
     config.available_features.add("executable_test")
+    config.available_features.add("long_test")
 elif swift_run_only_tests == 'executable_tests':
     config.available_features.add("executable_test")
     config.limit_to_features.add("executable_test")