- made --extra-cflags option work on darwin

- allow INTER4V macroblocks for FLV1 codec
- fixed issue in flv file format saving 8 mp3 frames per packet instead of 1
- fixed crasher in flv file format involving mp3 buffer handling
- added FLV1 codec support for swf file format (FlashPlayer6 or above
required) and made it default
- fixed broken mp3 support in swf file format
patch by (Tinic Uro <turo at macromedia dot com>)
cleanup by me

Originally committed as revision 2756 to svn://svn.ffmpeg.org/ffmpeg/trunk