includedir -vs- glib.h

[Tom Tromey <tromey creche cygnus com>]

Right now glib.h is installed in $(includedir).  glib.h also has some
of the results from configure embedded in it.

This is wrong.  The contents of includedir should be shareable across
a heterogenous network.

Either glib.h should be installed elsewhere (somewhere beneath
$exec_prefix), or glib.h should not include the configuration
information.

Tom