avopt: Reorder the default_val struct, making i64 the first field

Also mention this change in APIchanges.
Signed-off-by: Martin Storsjö <martin@martin.st>

doc/APIchanges

@@ -13,6 +13,10 @@ libavutil:     2011-04-18
 
 API changes, most recent first:
 
+2012-09-04 - xxxxxxx - lavu 51.40.0 - opt.h
+  Reordered the fields in default_val in AVOption, changed which
+  default_val field is used for which AVOptionType.
+
 2012-xx-xx - xxxxxxx - lavc 54.26.1 - avcodec.h
   Add codec descriptor properties AV_CODEC_PROP_LOSSY and
   AV_CODEC_PROP_LOSSLESS.

libavutil/opt.h

@@ -261,10 +261,10 @@ typedef struct AVOption {
      * the default value for scalar options
      */
     union {
+        int64_t i64;
         double dbl;
         const char *str;
         /* TODO those are unused now */
-        int64_t i64;
         AVRational q;
     } default_val;
     double min;                 ///< minimum valid value for the option

libavutil/version.h

@@ -37,7 +37,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 39
+#define LIBAVUTIL_VERSION_MINOR 40
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \