[Build Script Helper] Add a --lit-test-dir flag

Author: porglezomp

Utilities/build-script-helper.py

@@ -192,6 +192,8 @@ def handle_invocation(args):
     if should_test_parallel():
       test_args += ['--parallel']
     env['SWIFT_DRIVER_ENABLE_INTEGRATION_TESTS'] = "1"
+    if args.lit_test_dir:
+      env['SWIFT_DRIVER_LIT_DIR'] = args.lit_test_dir
     swiftpm('test', swift_exec, test_args, env)
   elif args.action == 'install':
     if platform.system() == 'Darwin':
@@ -579,6 +581,7 @@ def add_common_args(parser):
     parser.add_argument('--build-path', metavar='PATH', default='.build', help='build in the given path')
     parser.add_argument('--foundation-build-dir', metavar='PATH', help='Path to the Foundation build directory')
     parser.add_argument('--dispatch-build-dir', metavar='PATH', help='Path to the Dispatch build directory')
+    parser.add_argument('--lit-test-dir', metavar='PATH', help='the test dir in the Swift build directory')
     parser.add_argument('--configuration', '-c', default='debug', help='build using configuration (release|debug)')
     parser.add_argument('--no-local-deps', action='store_true', help='use normal remote dependencies when building')
     parser.add_argument('--verbose', '-v', action='store_true', help='enable verbose output')
@@ -617,6 +620,9 @@ def add_common_args(parser):
   if args.foundation_build_dir:
     args.foundation_build_dir = os.path.abspath(args.foundation_build_dir)
 
+  if args.lit_test_dir:
+    args.lit_test_dir = os.path.abspath(args.lit_test_dir)
+
   # If a separate prefix has not been specified, installed into the specified toolchain
   if not args.install_prefixes:
     args.install_prefixes = [args.toolchain]