wasmstdlib.py: pass through args.lit_args as LLVM_LIT_ARGS

This fixes default `LLVM_LIT_ARGS` having values inconsistent with rest of the test targets configured by CMake.

Author: MaxDesiatov

utils/swift_build_support/swift_build_support/products/wasmstdlib.py

@@ -184,6 +184,7 @@ def _build_stdlib(self, host_target, target_triple, llvm_cmake_dir):
             self.build_dir, 'test-wasi-wasm32', path) for path in lit_test_paths]
         self.cmake_options.define('SWIFT_LIT_TEST_PATHS:STRING',
                                   ';'.join(lit_test_paths))
+        self.cmake_options.define('LLVM_LIT_ARGS', self.args.lit_args)
         test_driver_options = [
             # compiler-rt is not installed in the final toolchain, so use one
             # in build dir