[roll third_party/pigweed] pw_presubmit: adds a preserve_args_gn arg to build.gn_gn

This helps projects that copy an args.gn to the output
directory before calling build.gn_gen.

Also, when there are no gn_arguments, the --args is
not passed to `gn gen`

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98240

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: b641ad950547e2c..62b5e0502a643a9
Roller-URL: https://ci.chromium.org/b/8811257281128095409
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811257281128095409
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I395239ba50ccb916a44e33b01c6d5564025664f2
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/98284
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 b641ad9..62b5e05 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit b641ad950547e2c56e8be154087f27b8291b1846
+Subproject commit 62b5e0502a643a9b614a138961bf6c1fabe36fdf