gprofng: implement a functional gp-display-html

This patch enables the first support for the "gprofng display html" command.
This command works for C/C++ applications on x86_64. Using one or more gprofng
experiment directories as input, a new directory with html files is created.
Through the index.html file in this directory, the performance results may be
viewed in a browser.

gprofng/Changelog:
2022-06-28  Ruud van der Pas  <ruud.vanderpas@oracle.com>

	* gp-display-html/gp-display-html.in: implement first support for x86_64 and C/C++