fix 'lvalue required as left operand of assignment' errors

src/sound_aix.c

@@ -93,10 +93,10 @@ static void play(void *b, int i)
 	while (i) {
 		if ((j = write(audio_fd, b, i)) > 0) {
 			i -= j;
-			(char *)b += j;
+			b = (char *)b + j;
 		} else
 			break;
-	};
+	}
 }
 
 static void deinit(void)

src/sound_hpux.c

@@ -116,7 +116,7 @@ static void play(void *b, int i)
 	while (i) {
 		if ((j = write(audio_fd, b, i)) > 0) {
 			i -= j;
-			(char *)b += j;
+			b = (char *)b + j;
 		} else
 			break;
 	}