[tools] Pass through offsets extractor arguments to tools/build.py.

Allows the builds to be run with non-default arguments, for example:

dart tools/run_offsets_extractor.dart --no-rbe

Change-Id: I1299b156a40baab27db890c0b0ae5f2f945c4259
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/346361
Reviewed-by: Jonas Termansen <sortie@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
diff --git a/tools/run_offsets_extractor.dart b/tools/run_offsets_extractor.dart
index 06ebab7..09c220c 100755
--- a/tools/run_offsets_extractor.dart
+++ b/tools/run_offsets_extractor.dart
@@ -9,7 +9,7 @@
 
 final pool = Pool(Platform.numberOfProcessors);
 
-main() async {
+main(List<String> args) async {
   final sdkRoot = Platform.script.resolve('../').toFilePath();
   Directory.current = Directory(sdkRoot);
 
@@ -26,6 +26,7 @@
     print('Building $buildDir');
     await run([
       'tools/build.py',
+      ...args,
       '-a$arch',
       '-m$mode',
       'offsets_extractor',