Make run_tool.py less spammy after /showIncludes:user change.

follow-up to https://chromium-review.googlesource.com/c/chromium/src/+/2078738

TBR=hans

Bug: none
Change-Id: I4fb2eebbddd3687849ca87e74479d34e05d3edd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095439Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748443}

tools/clang/scripts/run_tool.py

@@ -221,7 +221,7 @@ def _ExecuteTool(toolname, tool_args, build_directory, compdb_entry):
         # /showIncludes is used by Ninja to track header file dependencies on
         # Windows. We don't need to do this here, and it results in lots of spam
         # and a massive log file, so we strip it.
-        and a != '/showIncludes'
+        and a != '/showIncludes' and a != '/showIncludes:user'
         # -MMD has the same purpose on non-Windows. It may have a corresponding
         # '-MF <filename>', which we strip below.
         and a != '-MMD'