Makefile: make LIBDIR configurable

On Fedora /usr/lib64 is used for 64 bit architectures.

[rydberg@euromail.se: removed extra slash]
Signed-off-by: Harald Hoyer <harald@redhat.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
diff --git a/Makefile b/Makefile
index c61f955..f9e5c0a 100644
--- a/Makefile
+++ b/Makefile
@@ -25,8 +25,9 @@
 OBJS	= $(addprefix obj/,$(OBJECTS))
 XOBJS	= $(addprefix obj/,$(XOBJECTS))
 LIBS	= -lmtdev -lm
+LIBDIR  = usr/lib
 
-DLIB	= usr/lib/xorg/modules/input
+DLIB	= $(LIBDIR)/xorg/modules/input
 
 INCLUDE = -Iinclude -I/usr/include/xorg -I/usr/include/pixman-1
 OPTS	= -O3 -fPIC