Fixed a few "-Wredundant-decls" warnings

src/audio/alsa/SDL_alsa_audio.c

@@ -98,7 +98,6 @@ static void (*ALSA_snd_pcm_info_set_device)(snd_pcm_info_t *, unsigned int);
 static void (*ALSA_snd_pcm_info_set_subdevice)(snd_pcm_info_t *, unsigned int);
 static void (*ALSA_snd_pcm_info_set_stream)(snd_pcm_info_t *, snd_pcm_stream_t);
 static int (*ALSA_snd_ctl_pcm_info)(snd_ctl_t *, snd_pcm_info_t *);
-static unsigned int (*ALSA_snd_pcm_info_get_subdevices_count)(const snd_pcm_info_t *);
 static const char *(*ALSA_snd_ctl_card_info_get_id)(const snd_ctl_card_info_t *);
 static const char *(*ALSA_snd_pcm_info_get_name)(const snd_pcm_info_t *);
 static const char *(*ALSA_snd_pcm_info_get_subdevice_name)(const snd_pcm_info_t *);

src/haptic/hidapi/SDL_hidapihaptic.c

@@ -27,8 +27,6 @@
 #include "SDL3/SDL_mutex.h"
 #include "SDL3/SDL_error.h"
 
-extern struct SDL_JoystickDriver SDL_HIDAPI_JoystickDriver;
-
 typedef struct haptic_list_node
 {
     SDL_Haptic *haptic;