Prevent inlining VERBATIM.

[1uc]

We're banning all VERBATIM blocks because the current solution failed to detect:

BREAKPOINT {
   SOLVE getonset
}

PROCEDURE getonset() {
   VERBATIM
   return 0;
   ENDVERBATIM
}

must not be inlined as:

void nrn_state_synp(...) {
// ...
    for (int id = 0; id < nodecount; id++) {
        // VERBATIM
        return 0; 
        // ENDVERBATIM
    }
}