Version 1.6.9 released with lots of fixes and more

Hi.

After a hiatus, I've decided to release version 1.6.9 into the wild.

It doesn't really contain many changes, but there are a few.

• Will now build Kodi with the system ffmpeg instead of the one bundled
• Will display the git revision when fetching updates
• Will now clean up the pid file if you hit Ctrl-C
• Added option to use USE_LTO in build.leia.conf
• Detects and lets you know if you're missing any libraries
• Bumped JSON_RPC to 9.1.1 (I need to find out if this hack is necessary)

Anyway, have a good time compiling and enjoying Kodi.