btrace: Print "non-contiguous" for gaps.

btrace: Print "non-contiguous" for gaps.

So far we printed "disabled" for gaps, when we saw a ptev_enabled event that
doesn't have the resumed flag set.  This is wrong, as the actual disabling
happens with ptev_disabled.  So far this didn't matter, but once we have event
tracing, there can be events between a ptev_disabled and a ptev_enabled.
This patch is in preparation for that, and removes the disabled reason in
favour of a more accurate non-contiguous reason, and adjusts the string we
print accordingly.

Approved-By: Markus Metzger <markus.t.metzger@intel.com>