fluidsynth: deal with glob() error cases correctly (and add debug)

glob() sets the result structure also in case of error. The results
may be incomplete.
(cherry picked from commit 85488575)

modules/codec/fluidsynth.c

@@ -105,6 +105,7 @@ static int Open (vlc_object_t *p_this)
     {
         const char *lpath = ToLocale (font_path);
 
+        msg_Dbg (p_this, "loading sound fonts file %s", font_path);
         p_sys->soundfont = fluid_synth_sfload (p_sys->synth, font_path, 1);
         LocaleFree (lpath);
         if (p_sys->soundfont == -1)
@@ -116,12 +117,12 @@ static int Open (vlc_object_t *p_this)
     {
         glob_t gl;
 
-        if (!glob ("/usr/share/sounds/sf2/*.sf2", GLOB_NOESCAPE, NULL, &gl))
-        {
+        glob ("/usr/share/sounds/sf2/*.sf2", GLOB_NOESCAPE, NULL, &gl);
         for (size_t i = 0; i < gl.gl_pathc; i++)
         {
             const char *path = gl.gl_pathv[i];
 
+            msg_Dbg (p_this, "loading sound fonts file %s", path);
             p_sys->soundfont = fluid_synth_sfload (p_sys->synth, path, 1);
             if (p_sys->soundfont != -1)
                 break; /* it worked! */
@@ -129,7 +130,6 @@ static int Open (vlc_object_t *p_this)
         }
         globfree (&gl);
     }
-    }
 #endif
 
     if (p_sys->soundfont == -1)