afl-clang-fast++ seems to miscompile this

doesn't harm to swap the order of comparisons, and include the failing testcase
for reference

Change-Id: I38399cca8f6085704ee714faa04fbbf283138c3d

sw/source/filter/ww8/ww8scan.cxx

@@ -1901,12 +1901,12 @@ sal_Int32 WW8ScannerBase::WW8ReadString( SvStream& rStrm, OUString& rStr,
         long nLen = ( (nNextPieceCp < nBehindTextCp) ? nNextPieceCp
             : nBehindTextCp ) - nAktStartCp;
 
-        if( 0 >= nLen )
-            break;
-
         if( nLen > USHRT_MAX - 1 )
             nLen = USHRT_MAX - 1;
 
+        if( 0 >= nLen )
+            break;
+
         rStr += bIsUnicode
              ? read_uInt16s_ToOUString(rStrm, nLen)
              : read_uInt8s_ToOUString(rStrm, nLen, eEnc);