bpf: do not use structured initialization for bpf_attr

bpf: do not use structured initialization for bpf_attr

It looks like zero'ing the struct is not enough, and with some level
of optimizations there is still non-zero padding left over.
Switch to member-by-member initialization. Also convert all remaining
bpf_attr variables in other files.

(cherry picked from commit 9ca600e2bfacc52a65c89f3485723b2c27394e55)