Add youtubeUnblock statistics

The statistis will be printed on exit in userspace version. In kernel
space version, use `cat /proc/kyoutubeUnblock`.

The feature was proposed by @IceCat74 in #220

src/args.c

@@ -26,6 +26,7 @@
 #include "getopt.h"
 #include "raw_replacements.h"
 
+struct statistics_data global_stats;
 
 /**
  * Logging definitions