gssize, gsize

[Owen Taylor <otaylor redhat com>]

Currently, glib.h has

 #define gint32 gssize
 #define guint32 gsize

This strikes me as a bad idea. On a 64 bit platforms, attempts to 
use these in place of ssize_t and size_t are going to produce warnings
and, in extreme cases, incorrect code.

If we don't want to simply include <stddef.h> and use size_t and ssize_t,
which strikes me as the right course. We should test for the sizes of
these types and mirror that in gssize and gsize.

Right?
                                        Owen