Feature-less implementation of count_substrings.
Feature-less implementation of count_substrings.

zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools