ofz#2899 increment pos before check, like all the other cases

Change-Id: Id49f747e36f767a3e82fc3610959eb94015a93d7
Reviewed-on: https://gerrit.libreoffice.org/40984Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

hwpfilter/source/drawing.h

@@ -318,8 +318,6 @@ static bool LoadCommonHeader(HWPDrawingObject * hdo, unsigned short * link_info)
 
 static HWPDrawingObject *LoadDrawingObject(void)
 {
-    fprintf(stderr, "LoadDrawingObject\n");
-
     HWPDrawingObject *hdo, *head, *prev;
 
     unsigned short link_info;

hwpfilter/source/hiodev.cxx

@@ -305,9 +305,10 @@ bool HMemIODev::setCompressed(bool )
 
 bool HMemIODev::read1b(unsigned char &out)
 {
+    ++pos;
     if (pos <= length)
     {
-        out = ptr[pos++];
+        out = ptr[pos - 1];
         return true;
     }
     return false;