We need object files to depend on the build directories, so that the build directories get created before we try to output files into them. But making them depend directly on the build directories means that whenever a build directory changes (including any change to the set of files inside it) all the source files get recompiled. So, instead, make them depend on dummy files inside the directories, which will only get modified if someone does it intentionally.
Linux kernel 2.4 specific build:
- Backports: compat-2.4/genetlink.c is a back-port of the
Linux 2.6 Generic Netlink functionality. It must be loaded
as module genetlink_mod.o before openflow_mod.o may be
loaded.