A new debugger.

Lots of bugs/rough edges/etc - issues will be filed.
Old-style debugging still works (just use --emit_source_annotations to get
the helpful movs back and --break_on_instruction will still fire).

src/xenia/cpu/stack_walker.h

@@ -13,8 +13,8 @@
 #include <memory>
 #include <string>
 
+#include "xenia/base/x64_context.h"
 #include "xenia/cpu/function.h"
-#include "xenia/cpu/x64_context.h"
 
 namespace xe {
 namespace cpu {
@@ -82,6 +82,7 @@ class StackWalker {
   virtual size_t CaptureStackTrace(void* thread_handle,
                                    uint64_t* frame_host_pcs,
                                    size_t frame_offset, size_t frame_count,
+                                   const X64Context* in_host_context,
                                    X64Context* out_host_context,
                                    uint64_t* out_stack_hash = nullptr) = 0;