xls: Defrowheight345 without pColRowBuff

Change-Id: I22be90d7c54b1118f81337bd9e1d97ba3a1fd86e
(cherry picked from commit 4eb26f9c)
Reviewed-on: https://gerrit.libreoffice.org/19109Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: David Tardon <dtardon@redhat.com>

sc/source/filter/excel/impop.cxx

@@ -1053,6 +1053,13 @@ void ImportExcel::Defrowheight345()
     sal_uInt16 nFlags, nDefHeight;
     nFlags = maStrm.ReaduInt16();
     nDefHeight = maStrm.ReaduInt16();
+
+    if (!pColRowBuff)
+    {
+        SAL_WARN("sc", "*ImportExcel::Defrowheight345(): pColRowBuff is NULL!");
+        return;
+    }
+
     pColRowBuff->SetDefHeight( nDefHeight, nFlags );
 }