clock: Backport Evolution calendar integration from gnome-panel

Add Evolution Data Server (EDS) calendar integration to the MATE panel
clock applet, most of it ported from gnome-panel's clock applet. This
allows users to view calendar events and tasks directly from the clock
popup calendar.

The calendar integration is disabled by default and can be enabled
with --enable-eds during configuration. When disabled, the clock
applet functions normally without any EDS dependencies.

Author: vkareh

applets/clock/Makefile.am

@@ -35,6 +35,15 @@ CLOCK_SOURCES = 		\
 	set-timezone.h		\
 	$(BUILT_SOURCES)
 
+if HAVE_EDS
+CLOCK_SOURCES += \
+	calendar-client.c	\
+	calendar-client.h	\
+	calendar-sources.c	\
+	calendar-sources.h	\
+	calendar-debug.h
+endif
+
 CLOCK_CPPFLAGS =						\
 	$(AM_CPPFLAGS)						\
 	$(LIBMATE_PANEL_APPLET_CFLAGS)				\
@@ -44,13 +53,21 @@ CLOCK_CPPFLAGS =						\
 	-DMATELOCALEDIR=\""$(datadir)/locale"\"	\
 	-DMATEWEATHER_I_KNOW_THIS_IS_UNSTABLE
 
+if HAVE_EDS
+CLOCK_CPPFLAGS += $(EDS_CFLAGS)
+endif
+
 CLOCK_LDADD =						\
 	../../libmate-panel-applet/libmate-panel-applet-4.la	\
 	$(CLOCK_LIBS)					\
 	$(LIBMATE_PANEL_APPLET_LIBS)				\
 	libsystem-timezone.la				\
 	-lm
 
+if HAVE_EDS
+CLOCK_LDADD += $(EDS_LIBS)
+endif
+
 test_system_timezone_SOURCES = 	\
 	test-system-timezone.c
 test_system_timezone_LDADD = libsystem-timezone.la