- assert that WITH_JANSSON and JANSSON_SONAME are defined consistently.
This check ensures that we can check at compile time that nm_json_vt()
will always fail (because JANSSON_SONAME) is undefined.
That is interesting, because this means you can do a compile time
for !WITH_JANSSON, and know if nm_json_vt() will *never* succeed.
With that, we could let the linker know when the code is unused
and remove all uses of nm_json_vt(), without using the traditional
conditional compilation with "#if WITH_JANSSON". But of course, we
currently don't do this micro optimization to remove defunct code.
- drop the "mode" helper variable and pass the flags directly to
dlopen().