[roll pigweed] pw_build: Allow cc_blob_library to handle relative paths

cc_blob_library currently sets every path to the absolute
path but for RBE all paths must come from the build root
and not absolute paths.  This change will allow for
everything to be based off the build root.

Test: Verified this generated the build files correct and built
      correctly with RBE and regular builds.
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98441

https://pigweed.googlesource.com/pigweed/pigweed
pigweed Rolled-Commits: 0117408af4b6c33..63271a2a6f28264
Roller-URL: https://ci.chromium.org/b/8807558643505245921
Cq-Cl-Tag: roller-builder:pigweed-zephyr-roller
Cq-Cl-Tag: roller-bid:8807558643505245921
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I2d806060406d913dbc43f9eb88e525f10fb884d0
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/103541
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
1 file changed
tree: 9c2da36b56c81f498d21de185f375facb5765c6a
  1. .gitmodules
  2. test.sh