* dtable.cc (build_fh_name): Set error in dummy fhandler when one is noted

during path_conv.
* fhandler.h (fhandler_base::set_error): New method.

winsup/cygwin/fhandler.h

@@ -125,6 +125,7 @@ class fhandler_base
  public:
   void set_name (path_conv &pc);
   int error () const {return pc.error;}
+  void set_error (int error) {pc.error = error;}
   bool exists () const {return pc.exists ();}
   int pc_binmode () const {return pc.binmode ();}
   device& dev () {return pc.dev;}