monitor: Pass-through for gdbstub (Jan Kiszka)

Create a monitor terminal and pass it through the gdbstub. This allows
to use gdb's monitor command to access the QEMU monitor. Works for all
commands except for non-detached migration and password retrieval (user
will receive error messages instead).

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6718 c046a42c-6fe2-441c-8c8c-71466251a162
