[spectrum] cosmetic: Use static where appropriate
[rbp] Remove PiAudio engine
[rbp] Add PiAudio sink
[spectrum] Draw spectrum as a single object

glDrawElements is called 256 times per frame, once for each bar. It is more efficient to batch up larger blocks.
This change draws the specrum with a single glDrawElements call.

Looking at visualisation in full screen mode, it used to top out at 75 fps. With this PR it can hit 125 fps.
Support uClibc compilation

partly based on aports from Alpine Linux:
http://code.ohloh.net/file?fid=Up3lAbVglPtyupfNPazFHQYMKM8&cid=Sr-nRbkkE8E&s=&fp=302485&mp=&projSelected=true#L0
Merge pull request #3920 from bkuhls/uclibc

Support uClibc compilation
videodb: cosmetic in SQL query
CVideoInfoTag/CMusicInfoTag: make sure not to overwrite sortable fields with empty values (fixes #13850)
videodb: never use cached lookups during database cleaning
videodb: fix database cleaning for file-level sources
Merge pull request #3924 from popcornmix/single_spectrum

[spectrum] Draw spectrum as a single object
[rbp] Allow paplayer to be enabled on Pi
[rbp/omxplayer] Suspend AE when playing audio
[rbp/omxplayer] Remove visualisation support

This is now handled by paplayer
Revert "[rbp/omxplayer] Ignore video stream in audio filetypes"

This reverts commit ca5119d8bd73a632e6006e77cba7f59a37c3dbb2.
Merge pull request #3925 from popcornmix/piaudio_sink

[rbp] Add Pi audio sink for ActiveAE
[AE] cleanup includes and change include paths to relative from root
[AE] remove unnecessary include to cores/AudioEngine now that paths are relative