backports: add backport version to all modules

backports: add backport version to all modules

We print out the backports version at runtime, but it
can also be useful to be able to determine it from the
installed modules.

As we already override module_init() to make all our
backported modules depend on compat.ko (in order to do
exactly this -- print out the version at runtime) also
add some MODULE_VERSION directives to it.

This results in, for example for mac80211, this:

$ /sbin/modinfo .../net/mac80211/mac80211.ko
filename:       .../net/mac80211/mac80211.ko
license:        GPL
description:    IEEE 802.11 subsystem
version:        backported from: Linux (next-20130405-0-g7df052b)
version:        backports: 6e0475b
srcversion:     6C298E6033E34EA8E223D7B
depends:        cfg80211,compat
vermagic:       3.8.0 SMP mod_unload modversions
parm:           max_nullfunc_tries:Maximum nullfunc tx tries before disconnecting (reason 4). (int)
parm:           max_probe_tries:Maximum probe tries before disconnecting (reason 4). (int)
parm:           probe_wait_ms:Maximum time(ms) to wait for probe response before disconnecting (reason 4). (int)
parm:           ieee80211_default_rc_algo:Default rate control algorithm for mac80211 to use (charp)

Fuck-yeah: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>