Function igImFontAtlasTextureBlockCopy 

pub unsafe extern "C" fn igImFontAtlasTextureBlockCopy(
    src_tex: *mut ImTextureData,
    src_x: c_int,
    src_y: c_int,
    dst_tex: *mut ImTextureData,
    dst_x: c_int,
    dst_y: c_int,
    w: c_int,
    h: c_int,
)