Mark unused paramter in utils.c
Add extern declaration for version.c strings
Fix missing extern declaration error for build_info.pl
Declare extern numurls in common header
Make extern declaration for program_name
Add extern declaration for program_arsgstring

In test.c, this patch changes the type of program_argstring to char *
from a const char *. This is because, we use a char * string in the rest
of the program and declare an extern accordingly. Removing the const
type helps in keeping the code cleaner at no extra cost.
Remove defensive assert in cookies.c
Supplement logical assumption assert with error message