[roll third_party/pigweed] pw_presubmit: Remove now-unnecessary flag

Original-Bug: 271299438
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/171670

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 514b73c7ac35076..5a1691e618e1312
Roller-URL: https://ci.chromium.org/b/8769509977078534785
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I0aeaf3dc2dcccf55c68c21c5e1bc46088d40bea1
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/171705
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 514b73c..5a1691e 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 514b73c7ac35076304d2f904e3ac9e3a4c2ad3a4
+Subproject commit 5a1691e618e131254dd75ad9f42e09afaf16ee06