Merge pull request swiftlang#33961 from owenv/swift-driver-lit-feature

Add an cplusplus_driver lit feature for use with tests not supported by swift-driver

Author: owenv

test/lit.cfg

@@ -613,6 +613,9 @@ else:
 if 'swift_evolve' in lit_config.params:
     config.available_features.add("swift_evolve")
 
+if not 'swift_driver' in lit_config.params:
+    config.available_features.add("cplusplus_driver")
+
 # Enable benchmark testing when the binary is found (has fully qualified path).
 if config.benchmark_o != 'Benchmark_O':
     config.available_features.add('benchmark')