[test] Add feature tag to allow LLVM 17-only tests to run

Author: bryanpkc

test/lit.cfg

@@ -463,6 +463,9 @@ if lit.util.which('xmllint'):
 if config.llvm_version_major >= "13":
     config.available_features.add('llvm-13')
 
+if config.llvm_version_major >= "17":
+    config.available_features.add('llvm-17')
+
 if config.enable_backtrace == "1":
     config.available_features.add("backtrace")