Add -Wshadow to bpf_cc_defaults am: c52a98dde5

Original change: https://android-review.googlesource.com/c/platform/system/bpf/+/3556203

Change-Id: I3c489136fafde3da2cd3a78079f5850a2d23f0c2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>