Fix FFI Parsing of Pointer Declaration Lists

[davnotdev]

struct MyStruct {
    uint8_t** a, *b, c;
};

When a struct is defined in this form, the "base type" of a, b, and c is uint8_t**, so a will be uint8_t**, b will be uint8_t***, and c will be uint8_t**. This PR fixes the issue and adds a test case for it.

[bwoebi]

This file is generated from ext/ffi/ffi.g, so you should fix that one too.

But thanks for fixing and the test!