makefile cleanups

0.7 requires dbus 1.1 or greater (for system bus activation), so make that
explicit, and remove compat code for D-Bus 0.6 and earlier.  Consolidate
the various glib pkgconfig checks into one, since most anything will require
gthread, glib, and gobject anyway.  Fixup the docs makefile to be more
automake-compatible and let 'make clean' actually work correctly when
docs are built.

src/named-manager/Makefile.am

@@ -4,6 +4,11 @@ noinst_LTLIBRARIES = libnamed-manager.la
 
 libnamed_manager_la_SOURCES = nm-named-manager.h nm-named-manager.c
 
-libnamed_manager_la_CPPFLAGS = $(DBUS_CFLAGS) $(GTHREAD_CFLAGS) -DNM_PKGDATADIR=\"$(pkgdatadir)\" -DNM_LOCALSTATEDIR=\"$(localstatedir)\" -DDBUS_API_SUBJECT_TO_CHANGE
+libnamed_manager_la_CPPFLAGS = \
+	$(DBUS_CFLAGS) \
+	$(GLIB_CFLAGS) \
+	-DNM_PKGDATADIR=\"$(pkgdatadir)\" \
+	-DNM_LOCALSTATEDIR=\"$(localstatedir)\" \
+	-DDBUS_API_SUBJECT_TO_CHANGE
 
-libnamed_manager_la_LIBADD = $(DBUS_LIBS) $(GTHREAD_LIBS)
+libnamed_manager_la_LIBADD = $(DBUS_LIBS) $(GLIB_LIBS)