[omxcodec] Add hardware decode to dvdplayer for Pi

Hijack the abandoned OpenMaxVideo codec
[omxcodec] Allow hwcodec for DVD
[omxcodec] Enable for dvd menus
[omxcodec] Add omx specific texture create/upload/delete functions
[omxcodec] Add shared pointer to delay shutdown of codec until buffers are returned
[omxcodec] Fix for aspect ratio in non-square pixel modes
[omxcodec] Report error when codec not enabled
Improved file buffering in CArchive.

CArchive already did some file buffering, but only on writes. Added the
equivalent code for reads. Also improved the write buffer case so that it
only ever issues sector-aligned writes (the read code does this from the
start). Shuffled various bits of code into the header file to squeeze a bit
more performance out of it.

Profiled the effect on CFileItemList::Archive(), which is one of the slow
parts of the process of reopening a media library, on a non-overclocked
Raspberry Pi. Times are in seconds:

TV shows (253 items)

Before          After
Mean   StdDev   Mean   StdDev  Confidence  Change
0.394  0.005    0.151  0.005   100.0%      +159.8%

Songs (4115 items)

Before          After
Mean   StdDev   Mean   StdDev  Confidence  Change
2.931  0.045    0.690  0.019   100.0%      +324.4%
[rbp/settings] Allow av sync type to be enabled

It works for dvdplayer
[omxcodec] Add deinterlace support
[omxplayer] Fix incorrect settings query that can cause video stutter

A change in CSettings was missed here, and results in the clock component not being configured correctly.
This doesn't apply the correct filtering to clock changes and can create video stutter
[omxplayer] Reduce rate of clock change to reduce video stutters
[omxcodec] Only do essential calls in texture thread
[omx] Use generic texture queue for alloc/destroy

Fix race condition on exit
[omxplayer] Always enable timestamp fifo mode.

This effectively makes avoid_fix_ts=0 unnecessary
[omxcodec] Fix for files with no valid pts values.
[omx] First call needs to be from texture thread
[omxcodec] Fix stall on seek/trickplay - need to reset start flag
[omxcodec] Make sure we have a valid context when video decode starts before first fanart is decoded
[omxplayer] Allow small audio packets to be concatenated to make better use of audio fifo

Some audio codecs produce small packets which causes a high overhead when submitting to GPU, and doesn't make full use of GPU side buffering.
TrueHD in particular can produce packets with 40 samples (so 1200 packets per second) which causes very high overhead.

What this aims to do is to concatenate audio packets until they approach the ideal audio packet size,
and then deal with the awkardness of concatenated planar formats.