pw_function: Extend CMake support
pw_function: Extend CMake support

Change-Id: Ib3d62c866eef5b16e58c707511ed7473599cd96d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/79729
Pigweed-Auto-Submit: Ewout van Bekkum <638f134dbc68778d6b859fb04a64baea2b00b021@google.com>
Reviewed-by: Wyatt Hepler <cca3bedb37979eacd157a9bceb473582df8aea1e@google.com>
Commit-Queue: Auto-Submit <14637eda5603879df170705285bf30f5996692f0@pigweed.google.com.iam.gserviceaccount.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed