Merge "Export build flags to soong." into main am: 1acc860f

Original change: https://android-review.googlesource.com/c/platform/build/+/2795632



Change-Id: I61937fcf3be1caea530a1111565d07a9d570cff7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>