When giving authorisation errors from the proxy code in x11fwd.c,

name the proxy using the global 'appname' variable, instead of
statically calling it PuTTY.

(Knock-on effect is that PSCP and PSFTP have to declare that
variable, though of course they shouldn't ever actually _use_ the X
forwarding code. Probably I ought to replace it with a stub
nox11fwd.c for those applications.)

[originally from svn r8501]

pscp.c

@@ -50,6 +50,8 @@ static void source(char *src);
 static void rsource(char *src);
 static void sink(char *targ, char *src);
 
+const char *const appname = "PSCP";
+
 /*
  * The maximum amount of queued data we accept before we stop and
  * wait for the server to process some.