Rewinds the descriptor's next-index counter by one.
Declared in <wallet/scriptpubkeyman.h>
[[requires_capability(0x7f94fd518fc8), requires_capability(0x7f95058b9168), requires_capability(0x7f94f1e43f28), requires_capability(0x7f9505cb2c48), requires_capability(0x7f94f23e4448), requires_capability(0x7f94fd840b88)]]
void
DecIndex();