Initial support for emitting unwinding information in perf jitdump.

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index a5838794c3c65497ea6f9db24c7ffa7f70b69a93..9b59e45ac8eca6d183da6b3a717f50c6c6884d87 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -577,6 +577,8 @@ struct CodeDesc {
   int instr_size;
   int reloc_size;
   int constant_pool_size;
+  byte* unwinding_info;
+  int unwinding_info_size;
   Assembler* origin;
 };