Define SK_VULKAN for clang-tidy runs (flutter#21927)

When linting flutter/vulkan/vulkan_window.cc, the call to
GrDirectContext::MakeVulkan is undefined when SK_VULKAN is not defined,
triggering a lint error.

Bug: flutter#68331

Author: cbracken

ci/bin/lint.dart

@@ -28,6 +28,11 @@ https://github.com/flutter/flutter/wiki/Engine-Clang-Tidy-Linter
 
 const String issueUrlPrefix = 'https://github.com/flutter/flutter/issues';
 
+/// Symbol definitions passed to clang-tidy.
+const List<String> clangTidyDefineArgs = <String>[
+  "-DSK_VULKAN", // See: https://github.com/flutter/flutter/issues/68331
+];
+
 class Command {
   Directory directory = Directory('');
   String command = '';
@@ -46,6 +51,7 @@ String calcTidyArgs(Command command) {
   String result = command.command;
   result = result.replaceAll(RegExp(r'\S*clang/bin/clang'), '');
   result = result.replaceAll(RegExp(r'-MF \S*'), '');
+  result += ' ' + clangTidyDefineArgs.join(' ');
   return result;
 }
 

vulkan/vulkan_window.cc

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// FLUTTER_NOLINT: https://github.com/flutter/flutter/issues/68331
-
 #include "vulkan_window.h"
 
 #include <memory>