fpexif: Adapt to better work in Delphi.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7908 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpexif/fpeiptcdata.pas

@@ -247,13 +247,17 @@ var
   idx: Integer;
 begin
   if ATag = nil then
-    exit(-1);
+  begin
+    Result := -1;
+    exit;
+  end;
 
   idx := IndexOfTagID(ATag.TagID);
   if idx <> -1 then begin
     // Replace existing tag
     FTagList.Delete(idx);
     FTagList.Insert(idx, ATag);
+    Result := idx;
   end else
     // Add the new tag
     Result := FTagList.Add(ATag);