Added explicit index type in a for-loop in SoundBuffer.samples.get.
Added explicit index type in a for-loop in SoundBuffer.samples.get.

This should remove the warning about comparison between signed and
unsigned integers.

bastienleonard/pysfml-cython,mkeeter/pysfml2-cython,mkeeter/pysfml2-cython,bastienleonard/pysfml-cython