NetBpfLoad: Fail boot if BTF load fails on 4.19+

libbpf ignores BTF load error but this causes boot failure only when BTF
is required for some reasons (e.g. SK_STORAGE).
This CL makes boot fails regardless of the necessity of BTF on 4.19+
kernel

Test: boot kernel on 4.14, 4.19, 5.10, 6.1
Flag: EXEMPT mainline
Change-Id: I0af1e7eedcbea803c22c064ff157700a01307691
1 file changed