compiler, runtime: mark stub methods, ignore them in runtime.Caller.

    
    This fixes the long-standing bug in which the testing package misreports
    the file/line of an error.
    
    Reviewed-on: https://go-review.googlesource.com/19179

From-SVN: r233098

gcc/go/gofrontend/MERGE

-a408bef550251926c28673818db2c64302faac1d
+c70e74c116d08c6f2e787551eb1366983815c032
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/types.cc

@@ -9632,13 +9632,14 @@ Type::build_stub_methods(Gogo* gogo, const Type* type, const Methods* methods,
 	package = NULL;
       else
 	package = type->named_type()->named_object()->package();
+      std::string stub_name = name + "$stub";
       Named_object* stub;
       if (package != NULL)
-	stub = Named_object::make_function_declaration(name, package,
+	stub = Named_object::make_function_declaration(stub_name, package,
 						       stub_type, location);
       else
 	{
-	  stub = gogo->start_function(name, stub_type, false,
+	  stub = gogo->start_function(stub_name, stub_type, false,
 				      fntype->location());
 	  Type::build_one_stub_method(gogo, m, buf, stub_params,
 				      fntype->is_varargs(), location);

libgo/runtime/go-callers.c

@@ -74,6 +74,8 @@ callback (void *data, uintptr_t pc, const char *filename, int lineno,
       p = __builtin_strrchr (function, '$');
       if (p != NULL && __builtin_strcmp(p, "$recover") == 0)
 	return 0;
+      if (p != NULL && __builtin_strncmp(p, "$stub", 5) == 0)
+	return 0;
     }
 
   if (arg->skip > 0)