Add .exe to the produced executable for the protoc compiler.

Use include_dirs instead of -isystem. Remove some more warnings that
that causes.

Cq-Include-Trybots: luci.v8.try:v8_linux64_perfetto_dbg_ng
Bug: v8:8339
Change-Id: Ia6b0df63107470ec78f8038834205a0e4fe34b21
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1632069
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Auto-Submit: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61893}