use lit which

Signed-off-by: Sarnie, Nick <[email protected]>

Author: sarnex

clang/test/Tooling/lit.local.cfg

@@ -1,4 +1,4 @@
-import shutil
+import lit.util
 
 if not config.root.clang_staticanalyzer:
     config.unsupported = True
@@ -10,5 +10,5 @@ if config.spirv_tools_tests:
     config.substitutions.append(("spirv-as", os.path.join(config.llvm_tools_dir, "spirv-as")))
     config.substitutions.append(("spirv-link", os.path.join(config.llvm_tools_dir, "spirv-link")))
 
-if shutil.which("llvm-spirv"):
+if lit.util.which("llvm-spirv"):
     config.available_features.add("llvm-spirv")