patch 8.1.1999: calling both PlaySoundW() and PlaySoundA()

Problem:    Calling both PlaySoundW() and PlaySoundA().
Solution:   Only use PlaySoundW(). (Dan Thompson, closes #4903)

src/sound.c

@@ -435,7 +435,7 @@ f_sound_stop(typval_T *argvars, typval_T *rettv UNUSED)
     void
 f_sound_clear(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
 {
-    PlaySound(NULL, NULL, 0);
+    PlaySoundW(NULL, NULL, 0);
     mciSendString("close all", NULL, 0, NULL);
 }
 

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1999,
 /**/
     1998,
 /**/