roll: third_party/pigweed pw_build: Support executables with pw_py_importable_runfile

Slightly tweaks pw_py_importable_runfile to better support executables
that may have additional runfile dependencies, or live in an external
repository.

Original-Bug: b/388526733
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/268875
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: 94391ef6c7db8a3c05648dfd9ea034b590a961ef

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 2ac8a3ac33fac5..94391ef6c7db8a
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8722388558085385537
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I4b130b71c743f6d4221d544fc10ca0e71184da26
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/269652
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 2ac8a3a..94391ef 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 2ac8a3ac33fac50337152da174d40a73a49aa85a
+Subproject commit 94391ef6c7db8a3c05648dfd9ea034b590a961ef