fpexif: Avoid raising an exception when IPTC is present but has zero length. Issue #38876.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@8034 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpexif/fpeiptcreadwrite.pas

@@ -274,7 +274,7 @@ var
 begin
   FImgInfo.IptcData.Clear;
   if Length(ABuffer) = 0 then begin
-    Error(rsIptcDataExpected);
+    // IPTC block available but has zero length
     exit;
   end;