Copy the full line into the pbo. Dma will only take GL_UNPACK_ROW_LENGTH
- increase memcpy size by 2 in the pbo
+ single memcpy will be faster and can use sse
Enable buffer_storage extension:
* GL_CLIENT_STORAGE_BIT was required (it is the duty of TexSubImage to copy data into the GPU mem)
* Enable the extension by default