Fix autotest dry run

Fixes autotest dry run to print both the build and test run command,
instead of just the build command.

Change-Id: I8bbccacb2e8360f3a9066c4a02de5867d79542b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2565590
Auto-Submit: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831895}

tools/autotest.py

@@ -127,7 +127,7 @@ def BuildTestTargetsWithNinja(out_dir, targets, dry_run):
   cmd = [ninja_path, '-C', out_dir] + targets
   print('Building: ' + ' '.join(cmd))
   if (dry_run):
-    return
+    return True
   try:
     subprocess.check_call(cmd)
   except subprocess.CalledProcessError as e: