8058345: Refactor native stack printing from vmError.cpp to debug.cpp to make it available in gdb as well

Also fix stack trace on x86 to enable walking of runtime stubs and native wrappers

Reviewed-by: kvn

hotspot/src/share/vm/runtime/frame.hpp

@@ -68,6 +68,15 @@ class frame VALUE_OBJ_CLASS_SPEC {
   // Constructors
   frame();
 
+#ifndef PRODUCT
+  // This is a generic constructor which is only used by pns() in debug.cpp.
+  // pns (i.e. print native stack) uses this constructor to create a starting
+  // frame for stack walking. The implementation of this constructor is platform
+  // dependent (i.e. SPARC doesn't need an 'fp' argument an will ignore it) but
+  // we want to keep the signature generic because pns() is shared code.
+  frame(void* sp, void* fp, void* pc);
+#endif
+
   // Accessors
 
   // pc: Returns the pc at which this frame will continue normally.