Revert "Compile fix on windows -- vlc_mutex_init() now returns void."

Fix turns out to not be quite a fix.

This reverts commit ba8f1f35.

include/vlc_gcrypt.h

@@ -44,8 +44,12 @@ static int gcry_vlc_mutex_init( void **p_sys )
     if( p_lock == NULL)
         return ENOMEM;
 
-    vlc_mutex_init( p_lock );
-    return VLC_SUCCESS;
+    i_val = vlc_mutex_init( p_lock );
+    if( i_val )
+        free( p_lock );
+    else
+        *p_sys = p_lock;
+    return i_val;
 }
 
 static int gcry_vlc_mutex_destroy( void **p_sys )