Init mixer on cards with a single Mic control, like snd_usb_audio mics

[Jeff Cook]

This patch fixes bug #12706 and creates a mixer for snd-usb-audio cards, 
which have only a single Mic control and nothing else. Subsequent 
patches may be needed to make this useful depending on configuration.

I am including this here for commentary before I submit to wine-patches. 
This is my first patchset to WINE, so please forgive and correct me if I 
am "doing it wrong".

Thanks
Jeff
---
  dlls/winealsa.drv/mixer.c |   58 
++++++++++++++++++++++++++++++++++-----------
  1 files changed, 44 insertions(+), 14 deletions(-)