rpcrt4: A signed 1-bit bitfield doesn't make much sense; use unsigned.

include/rpcndr.h

@@ -204,19 +204,19 @@ typedef struct _MIDL_STUB_MESSAGE
   struct _FULL_PTR_XLAT_TABLES *FullPtrXlatTables;
   ULONG FullPtrRefId;
   ULONG PointerLength;
-  int fInDontFree:1;
-  int fDontCallFreeInst:1;
-  int fInOnlyParam:1;
-  int fHasReturn:1;
-  int fHasExtensions:1;
-  int fHasNewCorrDesc:1;
-  int fIsIn:1;
-  int fIsOut:1;
-  int fIsOicf:1;
-  int fBufferValid:1;
-  int fHasMemoryValidateCallback:1;
-  int fInFree:1;
-  int fNeedMCCP:1;
+  unsigned int fInDontFree:1;
+  unsigned int fDontCallFreeInst:1;
+  unsigned int fInOnlyParam:1;
+  unsigned int fHasReturn:1;
+  unsigned int fHasExtensions:1;
+  unsigned int fHasNewCorrDesc:1;
+  unsigned int fIsIn:1;
+  unsigned int fIsOut:1;
+  unsigned int fIsOicf:1;
+  unsigned int fBufferValid:1;
+  unsigned int fHasMemoryValidateCallback:1;
+  unsigned int fInFree:1;
+  unsigned int fNeedMCCP:1;
   int fUnused:3;
   int fUnused2:16;
   DWORD dwDestContext;