Function cmark_gfm_sys::cmark_render_xml_with_mem

pub unsafe extern "C" fn cmark_render_xml_with_mem(
    root: *mut cmark_node, 
    options: c_int, 
    mem: *mut cmark_mem
) -> *mut c_char

As for 'cmark_render_xml', but specifying the allocator to use for the resulting string.