dvdplayer: do not overwrite stream samplerate with zero

If the codec reports a sample rate of 0, do not use it to overwrite
stream sample rate from demuxer.

Found by elupus.
dvdplayer: add proper default implementation for GetEncodedSampleRate()

For non-passthrough codecs the content sample rate matches output sample
rate, so have GetEncodedSampleRate() return GetSampleRate().

Also drop the now unneeded specific implementation in
DVDAudioCodecFFmpeg.
fixed: broken checks
optimize two if conditions
Startup log: rearrange info for better readability
"x86 Linux 32-bit" -> "Linux x86 32-bit"
SystemInfo: add MIPS64 detection (for consistency)
Startup log: report OS similarly to platform ("Linux 32-bit" -> "Linux x86 32-bit")
* Add CSysInfo::GetKernelCpuFamily() function

Conflicts:
	xbmc/Application.cpp

Conflicts:
	xbmc/Application.cpp
Merge pull request #4672 from anssih/fix/dvdplayer-samplerate

dvdplayer sample rate fixes
Merge pull request #3990 from Karlson2k/startup_log_mod_01

Better readability for startup log
Merge pull request #4664 from Montellese/broken_checks

fix broken comparisons