[roll third_party/pigweed] CMake: Fix how missing backends are handled

- Replace references to the deleted null_backend.py script with an error
  message in CMake.
- Add the missing pw_log_null module.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/44600

third_party/pigweed Rolled-Commits: 94705a90a64ad4a..b59d2c968b458be
Roller-URL: https://ci.chromium.org/b/8847307896450219424
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8847307896450219424
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Iceed8c5dc14f1caa3b7b16364ad929096e7ff225
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/45302
Reviewed-by: 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>
1 file changed
tree: ebb6bc2091a786fd5b64909c730dbaaabfd81ddd
  1. applications/
  2. build_overrides/
  3. pw_board_led/
  4. pw_board_led_arduino/
  5. pw_board_led_host/
  6. pw_board_led_stm32cubef4/
  7. pw_board_led_stm32f429i_disc1/
  8. pw_spin_delay/
  9. pw_spin_delay_arduino/
  10. pw_spin_delay_host/
  11. pw_spin_delay_stm32cubef4/
  12. pw_spin_delay_stm32f429i_disc1/
  13. pw_sys_io_stm32cubef4/
  14. targets/
  15. third_party/
  16. tools/
  17. .gitattributes
  18. .gitignore
  19. .gitmodules
  20. .gn
  21. activate.bat
  22. banner.txt
  23. bootstrap.bat
  24. bootstrap.sh
  25. BUILD.gn
  26. BUILDCONFIG.gn
  27. env_setup.json
  28. navbar.md
  29. PW_PLUGINS
  30. README.md
README.md

Pigweed Experimental

This repository contains experimental pigweed modules.

Repository setup

Clone this repo with --recursive to get all required submodules.

git clone --recursive https://pigweed.googlesource.com/pigweed/experimental

This will pull the Pigweed source repository into third_party/pigweed. If you already cloned but forgot to --recursive run git submodule update --init to pull all submodules.