gprofng: fix bug 29352 - Fix the message Hexadecimal number > 0xffffffff non-portable

gprofng/Changelog:
2022-07-22  Ruud van der Pas  <ruud.vanderpas@oracle.com>

	PR gprofng/29352
	* gp-display-html/gp-display-html.in: the hex subroutine from
	the bigint module is now used.