Merge pull request swiftlang#21352 from compnerd/lit-erally-better-on-windows

lit improvements for Windows expansions

Author: compnerd

test/lit.cfg

@@ -817,13 +817,15 @@ elif run_os in ['windows-msvc']:
                                                       config.swift_test_options, \
                                                       config.swift_frontend_test_options))
 
-    config.target_codesign = ''
+    config.target_codesign = 'echo'
 
     subst_target_swift_frontend_mock_sdk = config.target_swift_frontend
     subst_target_swift_frontend_mock_sdk_after = ''
 
     config.target_build_swift_dylib =                                            \
-            ("%r -parse-as-library -emit-library -o '\\1'" % (config.target_build_swift))
+            SubstituteCaptures("%s -parse-as-library -emit-library -o \\1" % (config.target_build_swift))
+    config.target_add_rpath = r''
+
     config.target_clang =                                                        \
             ('clang++ -target %s %s' % (config.variant_triple, clang_mcp_opt))
     config.target_ld =                                                           \