ofz#3110 GeneratePLCF only generated word6 sized missing entries

BTE was 2 bytes in word 7- but 4 bytes in word 8+

Change-Id: I24007d26fccc5edc104320bd2eb8f9c62399c988
Reviewed-on: https://gerrit.libreoffice.org/41623Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sw/source/filter/ww8/ww8scan.cxx

@@ -2158,7 +2158,7 @@ void WW8PLCF::GeneratePLCF(SvStream& rSt, sal_Int32 nPN, sal_Int32 ncpN)
 
     if (!failure)
     {
-        size_t nSiz = 6 * nIMax + 4;
+        size_t nSiz = (4 + nStru) * nIMax + 4;
         size_t nElems = ( nSiz + 3 ) / 4;
         pPLCF_PosArray.reset( new sal_Int32[ nElems ] ); // Pointer to Pos-array
 
@@ -2213,7 +2213,7 @@ void WW8PLCF::GeneratePLCF(SvStream& rSt, sal_Int32 nPN, sal_Int32 ncpN)
         for (sal_Int32 i = 0; i < ncpN; ++i)         // construct PNs
         {
             ShortToSVBT16(static_cast<sal_uInt16>(nPN + i), p);
-            p+=2;
+            p += nStru;
         }
     }