APIchanges: fill in missing hashes and dates.

doc/APIchanges

@@ -13,29 +13,29 @@ libavutil:   2011-04-18
 
 API changes, most recent first:
 
-2011-07-xx - xxxxxxx - lavf 53.3.0
+2011-07-10 - a67c061 - lavf 53.3.0
   Add avformat_find_stream_info(), deprecate av_find_stream_info().
 
-2011-07-xx - xxxxxxx - lavc 53.6.0
+2011-07-10 - 0b950fe - lavc 53.6.0
   Add avcodec_open2(), deprecate avcodec_open().
 
-2011-06-xx - xxxxxxx - lavu 51.8.0 - attributes.h
+2011-06-23 - 67e9ae1 - lavu 51.8.0 - attributes.h
   Add av_printf_format().
 
-2011-06-xx - xxxxxxx - lavf 53.2.0 - avformat.h
+2011-06-16 - 05e84c9, 25de595 - lavf 53.2.0 - avformat.h
   Add avformat_open_input and avformat_write_header().
   Deprecate av_open_input_stream, av_open_input_file,
   AVFormatParameters and av_write_header.
 
-2011-06-xx - xxxxxxx - lavu 51.7.0 - opt.h
+2011-06-16 - 7e83e1c, dc59ec5 - lavu 51.7.0 - opt.h
   Add av_opt_set_dict() and av_opt_find().
   Deprecate av_find_opt().
   Add AV_DICT_APPEND flag.
 
-2011-06-xx - xxxxxxx - lavu 51.6.0 - opt.h
+2011-06-10 - cb7c11c - lavu 51.6.0 - opt.h
   Add av_opt_flag_is_set().
 
-2011-06-xx - xxxxxxx - lavu 51.5.0 - AVMetadata
+2011-06-08 - d9f80ea - lavu 51.5.0 - AVMetadata
   Move AVMetadata from lavf to lavu and rename it to
   AVDictionary -- new installed header dict.h.
   All av_metadata_* functions renamed to av_dict_*.
@@ -44,7 +44,7 @@ API changes, most recent first:
   Add av_get_bytes_per_sample() in libavutil/samplefmt.h.
   Deprecate av_get_bits_per_sample_fmt().
 
-2011-06-xx - xxxxxxx - lavu 51.3.0 - opt.h
+2011-06-05 - b39b062 - lavu 51.3.0 - opt.h
   Add av_opt_free convenience function.
 
 2011-05-28 - 0420bd7 - lavu 51.2.0 - pixdesc.h