eliminate os_core, move into base; eliminate regs, move into arch abstraction layer, define x64 regs in x64 layer; move win32 backend for os core (now base) functionality to top-level win32 layer

src/dwarf/dwarf_inc.h

@@ -16,5 +16,8 @@
 #include "dwarf/dwarf_parse_2.h"
 #include "dwarf/eh_frame.h"
 #include "dwarf/eh_dump.h"
+#if defined(X64_H)
+# include "dwarf/x64/dwarf_x64.h"
+#endif
 
 #endif // DWARF_INC_H