Debug: remove logger

Make a default logger and mapper in a .h file to be used by examples
Remove logger and mapper from libs
Make method to set the default mapper for the debug methods

spa/lib/meson.build

@@ -1,13 +1,11 @@
 spalib_headers = [
   'debug.h',
-  'mapper.h',
   'props.h',
 ]
 
 install_headers(spalib_headers, subdir : 'spa/lib')
 
 spalib_sources = ['debug.c',
-                  'mapper.c',
                   'props.c',
                   'format.c']