roll: third_party/pigweed: pw_assert: Remove backend multiplexer

Original-Bug: 347998044
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/215914
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https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: ef4e6e150fae762..e9f11670ffae078
Roller-URL: https://ci.chromium.org/b/8744111513362693633
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ide0f4d183e66e545f1d73e4a343d36c9b707c67d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/218315
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
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Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index ef4e6e1..e9f1167 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit ef4e6e150fae762fc1fcc4363c4a55d6eccaeb86
+Subproject commit e9f11670ffae078c0dd1918225074de2a6e3876c