Make cexpr available to product and vendor am: 94fcfdd31c

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/cexpr/+/2476330

Change-Id: Ice34668744deb51e36e643b351bd7321c242fbe9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>