maint: add myself to the copyright holders in posix.c.
maint: add myself to the copyright holders in posix.c.

* ext/posix/posix.c: Add myself to the copyright holders.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

ardje/luaposix,zevv/luaposix,jimmyharris/luaposix,snegovick/luaposix,ardje/luaposix,jimmyharris/luaposix,zevv/luaposix,luaposix/luaposix,rrthomas/luaposix,snegovick/luaposix,rrthomas/luaposix