Update the import table code to eliminate a few magic constants.

tools/widl/typelib_struct.h

@@ -153,17 +153,19 @@ typedef struct tagMSFT_TypeInfoBase {
                                 /*                 loword is num of inherited interfaces */
         INT     res18;          /* always? 0 */
 /*060*/ INT     res19;          /* always? -1 */
-    } MSFT_TypeInfoBase;
+} MSFT_TypeInfoBase;
 
 /* layout of an entry with information on imported types */
 typedef struct tagMSFT_ImpInfo {
-    INT     res0;           /* bits 0 - 15:  count */
+    INT     flags;          /* bits 0 - 15:  count */
                             /* bit  16:      if set oGuid is an offset to Guid */
                             /*               if clear oGuid is a typeinfo index in the specified typelib */
                             /* bits 24 - 31: TKIND of reference */
     INT     oImpFile;       /* offset in the Import File table */
     INT     oGuid;          /* offset in Guid table or typeinfo index (see bit 16 of res0) */
-    } MSFT_ImpInfo;
+} MSFT_ImpInfo;
+
+#define MSFT_IMPINFO_OFFSET_IS_GUID 0x00010000
 
 /* function description data */
 typedef struct {

tools/widl/write_msft.c

@@ -1751,7 +1751,7 @@ static void add_dispatch(msft_typelib_t *typelib)
     guidentry.guid = iid_idispatch;
     guidentry.hreftype = 1;
     guidentry.next_hash = -1;
-    impinfo.res0 = 0x301 << 16;
+    impinfo.flags = TKIND_INTERFACE << 24 | MSFT_IMPINFO_OFFSET_IS_GUID;
     impinfo.oImpFile = impfile_offset;
     impinfo.oGuid = ctl2_alloc_guid(typelib, &guidentry);
     typelib->typelib_header.dispatchpos = alloc_importinfo(typelib, &impinfo) | 0x01;