roll: third_party/pigweed pw_build: Add -O and -g flags to rustflags

-O and -g flags specified through GN toolchains were missing from
rustflags.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/236392
Original-Revision: 07636c248fb8a85b6f015a979cc44360d38112b0

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 1f2a0feb810005..07636c248fb8a8
Roller-URL: https://ci.chromium.org/b/8735749986605319537
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ib9830ae64fb68fe5d5b090f7d1e881f5c074fced
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/238036
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 1f2a0fe..07636c2 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 1f2a0feb81000531f1ae7e9e26a845609c1beb78
+Subproject commit 07636c248fb8a85b6f015a979cc44360d38112b0