re PR go/66016 (Accessing nil Func's name results in crash)

	PR go/66016
runtime: Don't crash in Func.Name if the Func is nil.

Related to Go issue 10696

From-SVN: r222816

libgo/runtime/go-caller.c

@@ -231,6 +231,8 @@ String runtime_funcname_go (Func *f)
 String
 runtime_funcname_go (Func *f)
 {
+  if (f == NULL)
+    return runtime_gostringnocopy ((const byte *) "");
   return f->name;
 }