This patch adds the --crash option (already present in "xm dump-core")
to "virsh dump".  virDomainCoreDump already has a flags argument, so
the API/ABI is untouched.

* include/libvirt/libvirt.h.in (virDomainCoreDumpFlags): New flag for
  CoreDump
* src/test/test_driver.c (testDomainCoreDump): Do not crash
  after dump unless VIR_DUMP_CRASH is given.
* src/qemu/qemu_driver.c (qemudDomainCoreDump): Shutdown the domain
  instead of restarting it if --crash is passed.
* src/xen/xend_internal.c (xenDaemonDomainCoreDump): Support --crash.
* tools/virsh.c (opts_dump): Add --crash.
  (cmdDump): Map it to flags for virDomainCoreDump and pass them.