Add an SDL beep to allow the first beep to not block the console.

(successive beeps currently still will)

src/conio/ciolib.c

@@ -195,6 +195,7 @@ static int try_sdl_init(int mode)
 		cio_api.set_modepalette=bitmap_set_modepalette;
 		cio_api.map_rgb = bitmap_map_rgb;
 		cio_api.replace_font = bitmap_replace_font;
+		cio_api.beep = sdl_beep;
 		return(1);
 	}
 	return(0);

src/conio/sdl_con.c

@@ -1392,3 +1392,15 @@ int sdl_initciolib(int mode)
 	sdl_keylock=sdl.SDL_CreateMutex();
 	return(sdl_init(mode));
 }
+
+void
+sdl_beep(void)
+{
+        static unsigned char wave[2206];
+
+	if (wave[2205] == 0) {
+		xptone_makewave(440, wave, 2205, WAVE_SHAPE_SINE_SAW_HARM);
+		wave[2205] = 1;
+	}
+        xp_play_sample(wave, 2205, TRUE);
+}

src/conio/sdl_con.h

@@ -37,6 +37,7 @@ int sdl_get_window_info(int *width, int *height, int *xpos, int *ypos);
 int sdl_setpalette(uint32_t index, uint16_t r, uint16_t g, uint16_t b);
 void sdl_setwinsize(int w, int h);
 void sdl_setwinposition(int x, int y);
+void sdl_beep(void);
 #ifdef __cplusplus
 }
 #endif