Fix for finding the starting stack and instruction pointer hooks for
the active tasks in x86_64 ELF or compressed dumpfiles created by the
KVM "virsh dump --memory-only" facility.  Without the patch, the
backtraces of active tasks may show an invalid starting frame that
indicates "__schedule".  The fix displays the exception RIP and dumps
the register contents that are stored in the dumpfile header.  If the
active task was operating in the kernel, the backtrace continues from
there; if the task was operating in user-space, the backtrace is
complete at that point.
(anderson@redhat.com)