pthread is not portable, so we can't use a pthread mutex use GMutex instead.
And adapt their logging system to go through it
The code only uses the new 'optimized' bit slicer
Current code from zapping/zvbi as of 2018-03-14. Files copied are all LGPL v2+. Changes from original zvbi code: * Switch to gst-debug logging system * Use glib for endianness detection * Fix compilation warnings
