[Dawid Gajownik] Update Makefile to compile correctly with X.Org X11R7

src/Makefile

 # Set the C flags to include the GTK+ and Python libraries
 PYTHONVER = `python -c 'import sys; print sys.version[:3]'`
-CFLAGS = `pkg-config --cflags gtk+-2.0 pygtk-2.0` -fPIC -I/usr/include/python$(PYTHONVER) -I.
-LDFLAGS = `pkg-config --libs gtk+-2.0 pygtk-2.0`
+HAVE_XSCRNSAVER = $(shell pkg-config --exists xscrnsaver && echo 'YES')
+
+ifeq ($(HAVE_XSCRNSAVER),YES)
+# We link with libXScrnsaver from modular X.Org X11
+CFLAGS = `pkg-config --cflags gtk+-2.0 pygtk-2.0 xscrnsaver` -fpic -I/usr/include/python$(PYTHONVER) -I.
+LDFLAGS = `pkg-config --libs gtk+-2.0 pygtk-2.0 xscrnsaver`
+else
+# We link with libXScrnsaver from monolithic X.Org X11
+CFLAGS = `pkg-config --cflags gtk+-2.0 pygtk-2.0` -fpic -I/usr/include/python$(PYTHONVER) -I.
+LDFLAGS = `pkg-config --libs gtk+-2.0 pygtk-2.0` -L/usr/X11R6$(LIBDIR) -lX11 -lXss -lXext
+endif
 
 all: trayicon.so gtkspell.so