twain: Make structures respect 2 byte packing requirements.

dlls/twain/twain.h

@@ -57,6 +57,9 @@
 #include "windef.h"
 #include "winbase.h"
 
+/* The Twain structures must be packed on 2 byte alignment */
+#include "pshpack2.h"
+
 #undef FAR
 #define FAR
 #define huge
@@ -1861,4 +1864,7 @@ typedef TW_UINT16 (*DSENTRYPROC)(pTW_IDENTITY,
 }
 #endif  /* cplusplus */
 
+/* The Twain structures must be packed on 2 byte alignment */
+#include "poppack.h"
+
 #endif  /* TWAIN */