cute_sound.h - fix for multiple looping sounds causing pop

[manbearcar]

Hi, I had an issue with playing two looping sounds at the same time. When one sound looped it would cause a little glitch.

at line 2452, samples_needed -= samples_to_write; is affecting every subsequent sound.

so I just made a fix by resetting samples_needed to it's initial value at the top of the do loop.

Hope this makes sense!

[RandyGaul]

Make a pull request :)