RE: [RFC] test: split up BPF tests

[Marat Khalili <marat.khalili@huawei.com>]

> The BPF tests have two sections. One is doing tests of the
> BPF interpreter and the other is for testing the ELF load part.
> The latter requires the null PMD to work, so only build it
> present.

Splitting BPF tests into multiple files makes sense, and not just because of
dependencies.

Coupling ELF tests with the presence of null PMD is strange, there might be a
lot of BPF ELF tests that do not depend on null or any PMD, and there might be
other BPF tests depending on PMD. Maybe we should call the new file
test_bpf_ethdev.c instead (following the header name rte_bpf_ethdev.h ,
regardless of what one thinks of the name), or something like this.