Only build alsa when detected by configure
Only build alsa when detected by configure

Original commit message from CVS:
Only build alsa when detected by configure

Distrotech/gstreamer,lubosz/gstreamer,krichter722/gstreamer,ensonic/gstreamer,magcius/gstreamer,lovebug356/gstreamer,jpakkane/gstreamer,justinjoy/gstreamer,shelsonjava/gstreamer,magcius/gstreamer,surround-io/gstreamer,krichter722/gstreamer,ahmedammar/platform_external_gst_gstreamer,lovebug356/gstreamer,lubosz/gstreamer,ensonic/gstreamer,magcius/gstreamer,Distrotech/gstreamer,krieger-od/gstreamer,ylatuya/gstreamer,cfoch/gstreamer,cablelabs/gstreamer,cfoch/gstreamer,collects/gstreamer,jpxiong/gstreamer,mparis/gstreamer,centricular/gstreamer,surround-io/gstreamer,Lachann/gstreamer,drothlis/gstreamer,krichter722/gstreamer,cfoch/gstreamer,lubosz/gstreamer,justinjoy/gstreamer,justinjoy/gstreamer,krieger-od/gstreamer,jpakkane/gstreamer,StreamUtils/gstreamer,magcius/gstreamer,justinjoy/gstreamer,Lachann/gstreamer,cablelabs/gstreamer,mparis/gstreamer,krieger-od/gstreamer,ylatuya/gstreamer,lovebug356/gstreamer,Lachann/gstreamer,surround-io/gstreamer,shelsonjava/gstreamer,lovebug356/gstreamer,shelsonjava/gstreamer,mrchapp/gstreamer,Lachann/gstreamer,krichter722/gstreamer,drothlis/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,krieger-od/gstreamer,lovebug356/gstreamer,ahmedammar/platform_external_gst_gstreamer,mrchapp/gstreamer,Lachann/gstreamer,mparis/gstreamer,cablelabs/gstreamer,krieger-od/gstreamer,collects/gstreamer,centricular/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,ensonic/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,mrchapp/gstreamer,surround-io/gstreamer,Distrotech/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,krichter722/gstreamer,justinjoy/gstreamer,cfoch/gstreamer,ahmedammar/platform_external_gst_gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,ylatuya/gstreamer,drothlis/gstreamer,collects/gstreamer,ensonic/gstreamer,ensonic/gstreamer,centricular/gstreamer,jpxiong/gstreamer,magcius/gstreamer,ahmedammar/platform_external_gst_gstreamer,mrchapp/gstreamer,Distrotech/gstreamer,jpakkane/gstreamer,jpxiong/gstreamer,Distrotech/gstreamer,StreamUtils/gstreamer,drothlis/gstreamer,drothlis/gstreamer,lubosz/gstreamer,collects/gstreamer,collects/gstreamer,mparis/gstreamer,centricular/gstreamer,jpakkane/gstreamer,ylatuya/gstreamer,ylatuya/gstreamer,ahmedammar/platform_external_gst_gstreamer,mrchapp/gstreamer,jpakkane/gstreamer,jpxiong/gstreamer,lubosz/gstreamer,cfoch/gstreamer,jpxiong/gstreamer