Fixed some compiler errors and warnings.

diff --git a/programs/winhelp/hlpfile.c b/programs/winhelp/hlpfile.c
index d06655d..9948441 100644
--- a/programs/winhelp/hlpfile.c
+++ b/programs/winhelp/hlpfile.c
@@ -5,7 +5,9 @@
  */
 
 #include <stdio.h>
+#include <string.h>
 #include "windows.h"
+#include "windowsx.h"
 #include "winhelp.h"
 
 static void Report(LPCSTR str)