Makefile: use Debian package versioning information for BUILD_TIME

Lets see what Jenkins provides us :)

From: Michael Prokop <mprokop@sipwise.com>

daemon/Makefile

@@ -60,7 +60,7 @@ clean:
 	$(CC) $(CFLAGS) -M $(SRCS) | sed -e 's/:/ .depend:/' > .depend
 
 build_time.h:	$(SRCS) Makefile
-	date +"#define BUILD_TIME \"%Y-%m-%d %H:%M:%S\"" > build_time.h
+	echo "#define BUILD_TIME \"$(shell dpkg-parsechangelog -l../debian/changelog | awk '/^Version: / {print $$2}')\"" > build_time.h
 
 mediaproxy-ng:	$(OBJS) .depend build_time.h
 	$(CC) $(CFLAGS) -o $@ $(OBJS) $(LDFLAGS)