[pkv/vm] Add package config to --depfile test fix 2

Depfiles escape backslashes with backslashes to be able to encode
spaces in paths. And they have backslashes on windows and forward
slashes on the other platforms.
Change the test to only check for the directory and file names, not
the path separators.

TEST=pkg/vm/test/kernel_front_end_test.dart

Change-Id: I15927d036fa07fe0a03a6d2340a241453f777794
Cq-Include-Trybots: luci.dart.try:pkg-win-release-try,pkg-win-release-arm64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/398901
Reviewed-by: Derek Xu <[email protected]>
Commit-Queue: Daco Harkes <[email protected]>

Author: dcharkes

pkg/vm/test/kernel_front_end_test.dart

@@ -184,7 +184,11 @@ main() {
         ]);
         expect(
           File(outputDepfile()).readAsStringSync(),
-          stringContainsInOrder('$sdkDir/$packageConfigFile'.split('/')),
+          stringContainsInOrder(
+            // Don't check for any path separators to avoid having to deal with
+            // different slashes and back-slash escaping.
+            '$sdkDir/$packageConfigFile'.replaceAll(r'\', '/').split('/'),
+          ),
         );
       },
       timeout: Timeout.none,