Handle timeout on duplex call

Previously, clnt_vc_call wasn't returning RPC_TIMEDOUT on duplex calls
that timed out.

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Use realtime clock for cond_timedwait timeouts

This should get rid of some of the spurious timeouts. For improved
performance we use CLOCK_REALTIME_FAST (which is defined to
CLOCK_REALTIME_COARSE on Linux.)

Signed-off-by: Adam C. Emerson <aemerson@linuxbox.com>
Serialize gss_wrap/gss_unwrap.

A small degree of unserialization could be achieved by moving
the critical section into the wrap/unwrap routines in authgss_prot.c,
but the potential gain looks small.

Signed-off-by: Matt Benjamin <matt@linuxbox.com>