Don't use ALSA on Windows.

src/xpdev/Common.gmake

@@ -214,6 +214,7 @@ ifndef WITHOUT_PORTAUDIO
   endif
  endif
 endif
+ifndef win
 	ifndef WITHOUT_ALSA_SOUND
 		ifeq ($(shell if [ -f /usr/include/alsa/asoundlib.h ] ; then echo YES ; fi),YES)
 			XPDEV-MT_CFLAGS	+= -DUSE_ALSA_SOUND
@@ -225,6 +226,7 @@ ifndef WITHOUT_ALSA_SOUND
 			endif
 		endif
 	endif
+endif
 
 ifndef NO_PULSEAUDIO
  ifeq ($(shell command -v pkg-config > /dev/null && pkg-config --exists libpulse-simple && echo 'YES'),YES)