Introduce BP_CPU as a breakpoint type (Jan Kiszka)

Introduce BP_CPU as a breakpoint type (Jan Kiszka)

Add another breakpoint/watchpoint type to BP_GDB: BP_CPU. This type is
intended for hardware-assisted break/watchpoint emulations like the x86
architecture requires.

To keep the highest priority for BP_GDB breakpoints, this type is
always inserted at the head of break/watchpoint lists, thus is found
first when looking up the origin of a debug interruption.

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@5746 c046a42c-6fe2-441c-8c8c-71466251a162