user32: Change extra value for standard edit class to 6.

Civilization II crashes when trying to display an edit box when this
value is anything other than six. It crashes in exactly the same way
on Windows XP 64-bit.

dlls/user32/edit.c

@@ -5425,7 +5425,11 @@ const struct builtin_class_descr EDIT_builtin_class =
     CS_DBLCLKS | CS_PARENTDC,   /* style */
     EditWndProcA,         /* procA */
     EditWndProcW,         /* procW */
+#ifdef _WIN64
     sizeof(EDITSTATE *),  /* extra */
+#else
+    sizeof(EDITSTATE *) + sizeof(HANDLE16), /* extra */
+#endif
     IDC_IBEAM,            /* cursor */
     0                     /* brush */
 };