This patch prepares the QEMU cpu_watchpoint/breakpoint API to allow the
succeeding enhancements this series comes with.
First of all, it overcomes MAX_BREAKPOINTS/MAX_WATCHPOINTS by switching
to dynamically allocated data structures that are kept in linked lists.
This also allows to return a stable reference to the related objects,
required for later introduced x86 debug register support.
Breakpoints and watchpoints are stored with their full information set
and an additional flag field that makes them easily extensible for use
beyond pure guest debugging.
Finally, this restructuring lays the foundation for KVM to hook into
the debugging infrastructure, providing its own services where hardware
virtualization demands it. Once QEMUAccel is considered for merge,
those entry point should be included into its abstraction layer so that
accellerators can hook in even more cleanly.