Rewinds the descriptor's next-index counter by one.
Declared in <wallet/scriptpubkeyman.h>
[[requires_capability(0x7fbc76311328), requires_capability(0x7fbc81288148), requires_capability(0x7fbc7d507198), requires_capability(0x7fbc96777888), requires_capability(0x7fbc846b1928), requires_capability(0x7fbc8dc01248)]]
void
DecIndex();