Add method to set build/run mode

Author: ayylol

sycl/test-e2e/lit.cfg.py

@@ -16,6 +16,16 @@
 
 # Configuration file for the 'lit' test runner.
 
+# split-mode: Set if tests should run normally or with split build/run
+match lit_config.params.get("split-mode","both"):
+    case "run":
+        config.available_features.add("run-mode")
+    case "build":
+        config.available_features.add("build-mode")
+    case _:
+        config.available_features.add("run-mode")
+        config.available_features.add("build-mode")
+
 # name: The name of this test suite.
 config.name = "SYCL"