dict: move struct AVDictionary definition to dict.c

This makes struct AVDictionary fully opaque now that nothing
needs to access it directly any more.

Signed-off-by: Mans Rullgard <mans@mansr.com>

libavutil/dict.c

@@ -23,6 +23,11 @@
 #include "internal.h"
 #include "mem.h"
 
+struct AVDictionary {
+    int count;
+    AVDictionaryEntry *elems;
+};
+
 int av_dict_count(const AVDictionary *m)
 {
     return m ? m->count : 0;

libavutil/internal.h

@@ -39,11 +39,6 @@
 #include "timer.h"
 #include "dict.h"
 
-struct AVDictionary {
-    int count;
-    AVDictionaryEntry *elems;
-};
-
 #ifndef attribute_align_arg
 #if ARCH_X86_32 && AV_GCC_VERSION_AT_LEAST(4,2)
 #    define attribute_align_arg __attribute__((force_align_arg_pointer))