Use unconditional thread calls in gio and gobject

If threads are available we always enable threads in gobject, which
means all gio/gobject code can enable the unconditional thread calls.

This is a minor optimization since we avoid a bunch of unnecessary
is-threads-enabled checks.

https://bugzilla.gnome.org/show_bug.cgi?id=606775

configure.in

@@ -2349,6 +2349,7 @@ case $host in
     ;;
 esac
 
+AM_CONDITIONAL(HAVE_THREADS, [test "$have_threads" != "none"])
 AC_DEFINE_UNQUOTED(G_THREAD_SOURCE,"gthread-$have_threads.c",
 		   [Source file containing theread implementation])
 AC_SUBST(G_THREAD_CFLAGS)

gio/Makefile.am

@@ -41,6 +41,10 @@ TESTS = abicheck.sh pltcheck.sh
 endif
 endif
 
+if HAVE_THREADS
+THREAD_FLAGS=-DG_THREADS_MANDATORY
+endif
+
 AM_CPPFLAGS = \
 	-DG_LOG_DOMAIN=\"GLib-GIO\"			\
 	-I$(top_builddir)				\
@@ -48,6 +52,7 @@ AM_CPPFLAGS = \
 	-I$(top_srcdir)/glib				\
 	-I$(top_srcdir)/gmodule				\
 	$(GLIB_DEBUG_FLAGS)				\
+	$(THREAD_FLAGS)					\
 	-DG_DISABLE_DEPRECATED				\
 	-DGIO_COMPILATION				\
 	-DGIO_MODULE_DIR=\"$(GIO_MODULE_DIR)\"	

gobject/Makefile.am

@@ -6,12 +6,17 @@ include $(top_srcdir)/Makefile.decl
 
 SUBDIRS = . tests
 
+if HAVE_THREADS
+THREAD_FLAGS=-DG_THREADS_MANDATORY
+endif
+
 AM_CPPFLAGS = 					\
 	-DG_LOG_DOMAIN=\"GLib-GObject\"		\
 	-I$(top_srcdir)				\
 	-I$(top_srcdir)/glib			\
 	-I$(top_builddir)			\
 	$(GLIB_DEBUG_FLAGS)			\
+	$(THREAD_FLAGS)				\
 	-DG_DISABLE_DEPRECATED			\
 	-DGOBJECT_COMPILATION			\
 	-DG_DISABLE_CONST_RETURNS