gi/, gjs/: Do not use g_autofree

g_autofree is a GCCism which means that it will not work on any compiler
besides GCC and CLang.  As we are getting close to GNOME 3.24, this serves
as a temporary patch so that we can work on changing the code to smart
pointers which will handle the automatic releasing of allocations on the
heap in the next dev cycle.

Also, include tuple in gi/object.cpp as we are using items from there, and
compilers such as Visual Studio expect one to be quite specific about
the things that are included in the std namespace by including the headers
specifically.

https://bugzilla.gnome.org/show_bug.cgi?id=777597