#2 Fix Alsa Latency on some systems

[Mark McCurry]

On some system (mine being one of such), get excessive amounts of latency with alsa if the number of periods is not set.
Had the same issue over at ZynAddSubFX a while ago:
http://zynaddsubfx.git.sourceforge.net/git/gitweb.cgi?p=zynaddsubfx/zynaddsubfx;a=commit;h=12aefb3e0cc6e1de0df0a33fa034383802e28fc4
It was fixed by adding in a line using snd_pcm_hw_params_set_periods_near

The attached patch should fix the same issue as it applies to amSynth's ALSA driver.

[Mark McCurry]