Add several generic integer pairs printing functions

Add several generic integer pairs printing functions

Add functions to fetch and print pairs of integer types.
Note that these printers do not attempt to fetch data
in case of exiting(tcp) && syserror(tcp).

printnum_* printers will follow as soon as all callers are made ready
for this change.

* defs.h (printpair_int, printpair_long, printpair_int64): New
prototypes.
* util.c (DEF_PRINTPAIR): New macro.
(printpair_int, printpair_long, printpair_int64): New functions.