[roll third_party/pigweed] pw_protobuf_compiler: Fix include file parsing

generate_protos.py has an optional input param of include_file. Ensure
that the script can still be run if include_file is None.

Test: Run script
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/74320

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 070ebff771b1c27..a3363ba3b795a02
Roller-URL: https://ci.chromium.org/b/8827667408460415441
Cq-Cl-Tag: roller-builder:pigweed-sample-project-roller
Cq-Cl-Tag: roller-bid:8827667408460415441
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I002aea3c182f1654080ac8d59030937d81fd7a8d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/sample_project/+/75100
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 070ebff..a3363ba 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 070ebff771b1c277fb01ea580c397864384ebf65
+Subproject commit a3363ba3b795a027767cd86c2ce85b9fe28b71d0