The header file is referenced by the part going to be mainlined in Netd.
Note that some platform visibility is required with this commit, since
users of bpf_shared.h is currently located in platform. The visibility
can be removed when all users are moved out of platform.
Bug: 202086915
Test: m; flash; boot
Test: cd system/netd && atest
Test: cd packages/modules/Connectivity && atest
Test: atest FrameworksNetTests
Change-Id: I5c16511b6a2d4eb80dfd93157cbc98d5030bd5ac
