Silence lots of warnings in lib/DtHelp.

* 64bit warnings
* Missing prototypes
* explicit parentheses / brackets

There's still some work to be done, but, as always, it's a start ...

cde/lib/DtHelp/SetList.c

@@ -67,6 +67,7 @@
 #include "DisplayAreaP.h"
 #include "CallbacksI.h"
 #include "FontAttrI.h"
+#include "FormatI.h"
 #include "SetListI.h"
 #include "XInterfaceI.h"
 #include "XUICreateI.h"