Add some missing "const"s

The one in msg.c was mistakenly removed with commit e99a37f6.

I didn't actually test the change in ao_sndio.c (but obviously "ap"
shouldn't be static).

audio/out/ao_sdl.c

@@ -38,7 +38,7 @@ struct priv
     float buflen;
 };
 
-static int fmtmap[][2] = {
+static const int fmtmap[][2] = {
     {AF_FORMAT_U8,      AUDIO_U8},
     {AF_FORMAT_S8,      AUDIO_S8},
     {AF_FORMAT_U16,     AUDIO_U16SYS},

audio/out/ao_sndio.c

@@ -111,7 +111,8 @@ static int init(struct ao *ao)
 
     struct af_to_par {
         int format, bits, sig;
-    } static const af_to_par[] = {
+    };
+    static const struct af_to_par af_to_par[] = {
         {AF_FORMAT_U8,   8, 0},
         {AF_FORMAT_S8,   8, 1},
         {AF_FORMAT_U16, 16, 0},
@@ -120,7 +121,8 @@ static int init(struct ao *ao)
         {AF_FORMAT_S24, 24, 1},
         {AF_FORMAT_U32, 32, 0},
         {AF_FORMAT_S32, 32, 1},
-    }, *ap;
+    };
+    const struct af_to_par *ap;
     int i;
 
     p->hdl = sio_open(p->dev, SIO_PLAY, 1);

common/msg.c

@@ -592,7 +592,7 @@ void mp_msg(struct mp_log *log, int lev, const char *format, ...)
     va_end(va);
 }
 
-const char *mp_log_levels[MSGL_MAX + 1] = {
+const char *const mp_log_levels[MSGL_MAX + 1] = {
     [MSGL_FATAL]        = "fatal",
     [MSGL_ERR]          = "error",
     [MSGL_WARN]         = "warn",

common/msg_control.h

@@ -31,7 +31,7 @@ int mp_msg_open_stats_file(struct mpv_global *global, const char *path);
 struct bstr;
 int mp_msg_split_msglevel(struct bstr *s, struct bstr *out_mod, int *out_level);
 
-extern const char *mp_log_levels[MSGL_MAX + 1];
+extern const char *const mp_log_levels[MSGL_MAX + 1];
 extern const int mp_mpv_log_levels[MSGL_MAX + 1];
 
 #endif

demux/codec_tags.c

@@ -352,8 +352,8 @@ static const char *lookup_tag(const struct mp_codec_tag *mp_table,
     return id == AV_CODEC_ID_NONE ? NULL : mp_codec_from_av_codec_id(id);
 }
 
-static const char *pcm_le[] = {"pcm_u8", "pcm_s16le", "pcm_s24le", "pcm_s32le"};
-static const char *pcm_be[] = {"pcm_s8", "pcm_s16be", "pcm_s24be", "pcm_s32be"};
+static const char *const pcm_le[] = {"pcm_u8", "pcm_s16le", "pcm_s24le", "pcm_s32le"};
+static const char *const pcm_be[] = {"pcm_s8", "pcm_s16be", "pcm_s24be", "pcm_s32be"};
 
 static const char *map_audio_pcm_tag(uint32_t tag, int bits)
 {

sub/osd.h

@@ -219,8 +219,8 @@ void osd_destroy_backend(struct osd_state *osd);
 
 // doesn't need locking
 void osd_get_function_sym(char *buffer, size_t buffer_size, int osd_function);
-extern const char *osd_ass_0;
-extern const char *osd_ass_1;
+extern const char *const osd_ass_0;
+extern const char *const osd_ass_1;
 
 // defined in backend, but locks if required
 void osd_object_get_resolution(struct osd_state *osd, int obj,

sub/osd_dummy.c

@@ -6,8 +6,8 @@
 #include "talloc.h"
 #include "osd.h"
 
-const char *osd_ass_0 = "";
-const char *osd_ass_1 = "";
+const char *const osd_ass_0 = "";
+const char *const osd_ass_1 = "";
 
 void osd_init_backend(struct osd_state *osd)
 {

sub/osd_libass.c

@@ -160,8 +160,8 @@ void osd_get_function_sym(char *buffer, size_t buffer_size, int osd_function)
 }
 
 // Same trick as above: never valid UTF-8, so we expect it's free for use.
-const char *osd_ass_0 = "\xFD";
-const char *osd_ass_1 = "\xFE";
+const char *const osd_ass_0 = "\xFD";
+const char *const osd_ass_1 = "\xFE";
 
 static void mangle_ass(bstr *dst, const char *in)
 {

video/out/gl_common.c

@@ -343,7 +343,7 @@ static const struct gl_functions gl_functions[] = {
     },
     {
         .extension = "GLX_SGI_video_sync",
-        .functions = (struct gl_function[]) {
+        .functions = (const struct gl_function[]) {
             DEF_FN_NAMES(GetVideoSync, "glXGetVideoSyncSGI"),
             DEF_FN_NAMES(WaitVideoSync, "glXWaitVideoSyncSGI"),
             {0},