Optimize memory management to create an av_packet from multiple slices: - remove memmove to pack the data, instead copy only the used areas  from the temp buffer in their final position - use the minimum possible size for the av_packet (relevant when some  slices are missing)
Optimize memory management to create an av_packet from multiple slices:
- remove memmove to pack the data, instead copy only the used areas 
from the temp buffer in their final position
- use the minimum possible size for the av_packet (relevant when some 
slices are missing)


git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@11052 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg