use PACKAGE_NAME in version.c, not sysname

I was trying to learn how to use GNU global with emacs and was surprised
that M-x semanticdb-enable-gnu-global-databases gave an error that it can't
find the version number of GNU Global. Turns out the problem is that
--version no longer identifies the program as *GNU* global. It simply says
"global (Global) 6.6.10".

The solution is to change line 66 of libutil/version.c so that it uses
PACKAGE_NAME instead of sysname.

    66 fprintf(stdout, "%s (%s) %s\n", name, PACKAGE_NAME, VERSION);

After using PACKAGE_NAME, it works correctly:

$ ./global/global --version
global (GNU GLOBAL) 6.6.10
Powered by Berkeley DB 1.85.
Copyright (c) 1996-2023 Tama Communications Corporation
License GPLv3+: GNU GPL version 3 or later <
http://www.gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Thanks!

--b9