Recently, it was reported to me that you could provoke a double fault

panic with the NDISulator if you did "ifconfig ndis0 10.0.0.1/24,"
whereas "ifconfig ndis0 10.0.0.1/24 up" worked fine. The double fault
was caused by the ifconfig thread running out of kernel stack space.
(This was partly due to the NDIsulator using a couple of big buffers on
the stack, but even after fixing that the double fault persisted.)

It turns out that ndis_init() is called in both cases, but in the first
case the code path passes through ieee80211_ioctl(), and it turns out
ieee80211_ioctl() consumes a whopping 2400 bytes of stack space.
Apparently, gcc -O2 causes the ieee80211_ioctl_get80211() routine to
be inlined into ieee80211_ioctl(), and for some reason which I do not
fully understand, this causes ieee80211_ioctl() to consume an extra 2K
of stack space.

To prevent this overly agressive optimization, ieee80211_ioctl_get80211()
is now declared with __attribute__ ((noinline)). With this change,
ieee80211_ioctl() now only reserves about 200 bytes of stack instead of 2400.

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