The Makefile rules in glib-tap.mk were copied from an example that
assumed that all the test programs had names ending in ".test", so
they didn't actually have any effect for us and resulted in us still
using the standard automake test driver. Fix this so we actually do
use TAP now.
https://bugzilla.gnome.org/show_bug.cgi?id=711796
Convert {glib,gobject,gio}/tests to use the automake TAP driver
and test harness instead of gtester. To do so, we add a glib-tap.mk
that provides the same interface as glib.mk, except for the
reporting and coverage testing functionality. Eventually, we may
want to replace glib.mk with it. I've not yet converted the
toplevel tests/ directory, since it mixes gtestutils tests with
other binaries.
https://bugzilla.gnome.org/show_bug.cgi?id=692125