Merge "system/btif: Enforce -Wmissing-prototypes" into main am: f9778e74

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Bluetooth/+/3504691



Change-Id: I35628a2f2e509524522929d311377ab74b566b2f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>