Revert "bpf: Remove bpf trampoline selector"

This reverts commit 8ea165e1 which is
commit 47e79cbe upstream.

It breaks the Android ABI and can be brought back in an abi-safe way in
the future if it is still needed.

Bug: 161946584
Change-Id: I6b0b4846d8ec26e44c6627b8b4cbb2c46cc01a13
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>