* Add map-in-map type checking
This PR enforces that all inner maps must be of the same type
as the inner map template used for verification. Other fields
might need to match too, and if so those will be updated in
a subsequent PR once it is confirmed which fields must match.
A few pieces of this PR related to map_id are prerequisites
for issue #396 which will add IDs for programs, maps, and links.
Finally, there are multiple definitions of bpf_map, since the
version used to write eBPF programs is different from what is
stored in memory (which uses map IDs) so to avoid confusion in
code and allow the compiler to do type checking to catch some
bugs, this splits ebpf_map_definition_t into two, one for
in_memory and one for in_file (meaning in an eBPF program).
This will also allow the future PR for issue 396 to be more
understandable, but also aids clarity in some parts of this PR.
Signed-off-by: Dave Thaler <dthaler@microsoft.com>
0a1555956e