Add kernel header support for bpf file mode

Add the bpf_attr field and define statement that are currently missing
in bionic uapi header. Once the upstream kernel v4.15 is released and
bionic header get updated, delete the corresponding headers from
BpfUtils.h.

Bug: 30950746
Test: system_server can access map in read only mode
Change-Id: Ie02fd9294d0556582ca5eacea959bf305fb3638d
2 files changed