If datanodes are only partially connected to the API nodes, a
particular SPJ node might get its request via a TC on another
node, without (yet) being connected to the API node itself.

The NodeInfo for the requesting API node will then not have
any valid info about the API nodes 'm_version', which then
is reported as '0'.

This caused DbSpj::abort() to incorrectly assume that the API
node is of version <= 7.2.5, which require a backward compatability
mode to be used during query abort. That involved sending
a 'nodeFailure' error instead of the real error as abort reason.

This patch assume that if m_version is not yet available,
the API node is of a more recent version that 7.2.4.
There are hardly any customers (none?) left on older
versions, so this should be a rather safe assumption.

In addition to the testcase, this patch extends the HugoQuery
framework such that the NdbError causing a failure can be get'ed.

It also fixes a potential issue where the Node_info::m_connected
member was not initialized by the Node_info constructor.