Function regexec_flags 

pub unsafe fn regexec_flags(
    my_perl: *mut PerlInterpreter,
    a: *mut REGEXP,
    b: *mut c_char,
    c: *mut c_char,
    d: *mut c_char,
    e: isize,
    f: *mut SV,
    g: *mut c_void,
    h: U32,
) -> I32

thx shim for crate::regexec_flags.