Function hv_common_key_len 

pub unsafe fn hv_common_key_len(
    my_perl: *mut PerlInterpreter,
    a: *mut HV,
    b: *const c_char,
    c: I32,
    d: c_int,
    e: *mut SV,
    f: U32,
) -> *mut c_void

thx shim for crate::hv_common_key_len.