Fixes #3993: Move r29963 to v1.7 branch (CSCul95082: DMAR faults during mtt)

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r29963 [[BR]]
CSCul95082: DMAR faults during mtt testing
    
usnic_channel_finalize() was deregistering recv buffers before
destroying the QP to which they were posted. The QP needs to be
destroyed first so that the NIC does not attemp tto write to
deregistered memory, causing the DMAR messages.

Submitted by Reese, reviewed by Jeff.

cmr=v1.7.4:reviewer=ompi-rm1.7
Fixes #3995: Move r29966 to v1.7 branch (two usnic btl fixes)

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r29966 [[BR]]
Remove CFLAGS setting that was really only intended for the v1.6
branch (it's not necessary on trunk/v1.7 because they require C99,
which allows variadic macros).

Also fix another compiler warning (using %p to print a (void*)).

Submitted by Jeff, reviewed by Dave.

cmr=v1.7.4:reviewer=ompi-rm1.7:subject=two usnic BTL fixes
1.7.4rc1 has escaped; on to rc2