Successfully tested with a dummy semantic patch:

    @@
    idexpression ctx, caller;
    @@

    -CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
    +AN(ctx);
     CHECK_OBJ_NOTNULL(caller, DEBUG_CALLER_MAGIC);
    -AN(caller->sub);
    +assert(caller->sub);

I decided to cram all definitions in the existing vdef.h file to keep
our relatively simple setup. We can add more macros as we learn what
coccinelle trips over.

Refs f5b0b201