hw/xwin: Fix const discarded warning in winGenerateAuthorization()

Fix const discarded warning in winGenerateAuthorization() in !XCSECURITY case

In function ‘winGenerateAuthorization’:
hw/xwin/winauth.c:123:38: warning: passing argument 2 of ‘GenerateAuthorization’ discards ‘const’ qualifier from pointer target type [enabled by default]
hw/xwin/winauth.c:99:1: note: expected ‘char *’ but argument is of type ‘const char *’

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>

hw/xwin/winauth.c

@@ -97,9 +97,9 @@ MitGenerateCookie(unsigned data_length,
 static
     XID
 GenerateAuthorization(unsigned name_length,
-                      char *name,
+                      const char *name,
                       unsigned data_length,
-                      char *data,
+                      const char *data,
                       unsigned *data_length_return, char **data_return)
 {
     return MitGenerateCookie(data_length, data,