Declare `struct RSAKey' so that its implicit declaration in the

parameter list of verify_ssh_host_key() does not have scope
restricted to that parameter list. Probably unnecessary but let's
not take chances.

[originally from svn r311]

putty.h

@@ -163,6 +163,8 @@ GLOBAL Config cfg;
 GLOBAL int default_protocol;
 GLOBAL int default_port;
 
+struct RSAKey;			       /* be a little careful of scope */
+
 /*
  * Exports from window.c.
  */