Propagate cpuDir into QnxToolChain

Add sdpPath and cpuDir comparison to QNX tool chain comparison.
Ensures that QnxConfiguration created tool chains don't get
removed just because they have the same ABI as another QNX
configuration created tool chain.

This should really be visible in the interface but that can be
done later since this isn't something that can currently happen
with official 6.6.0/7.0.0 SDPs.

Change-Id: Ibbb6a8aa645721028d1512460e51e59633b3cedc
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>
Reviewed-by: hjk <hjk@qt.io>