[KDGDB]
 - Add a callback mechanism permitting to "simulate" KD send <-> receive loop without having to actually communicate to GDB
 - Use that to update the program counter when cont'ing a breakpoint
Now cont'ing an assertion failure is possible, since we actually get beyond the int 3 instruction

git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@64127 97493ccd-5924-5043-b1f5-66cb403b36ce
[NTOSKRNL/GCC]
 - Use 0x00800000 as base address. This doesn't change anything (still loaded at 0x80800000) and it produces debug symbols that GDB can understand
[CMAKE]
 - Get back to using DWARF2 symbols. They are a lot bigger, but at least they work
Now GDB can be used to source-level debug ntoskrnl.

git-svn-id: svn://svn.reactos.org/reactos/trunk/reactos@64128 97493ccd-5924-5043-b1f5-66cb403b36ce