mandoc_xr_add
if (mandoc_xr_add(nch->next->string, nch->string, nch->line, nch->pos))
int mandoc_xr_add(const char *, const char *, int, int);
mandoc_xr_add(mdoc->meta.msec, n->child->string, -1, -1);
if(mandoc_xr_add(nch->next->string, nch->string,