Audio: don't export internal function.

src/Magnum/Audio/Context.h

@@ -190,7 +190,7 @@ class MAGNUM_AUDIO_EXPORT Context {
 
         /* Create a context with given configuration. Returns `true` on success.
          * @ref alcCreateContext(). */
-        bool tryCreateContext(const Configuration& config);
+        MAGNUM_AUDIO_LOCAL bool tryCreateContext(const Configuration& config);
 
         ALCdevice* _device;
         ALCcontext* _context;

src/Magnum/Audio/visibility.h

@@ -38,5 +38,6 @@
 #else
     #define MAGNUM_AUDIO_EXPORT CORRADE_VISIBILITY_STATIC
 #endif
+#define MAGNUM_AUDIO_LOCAL CORRADE_VISIBILITY_LOCAL
 
 #endif