tdf#112689 - Replace chained O(U)StringBuffer::append() with operator+

replaced use of append with operator+

Change-Id: I9eb36fd1f94475df57de7015f8dfabf95676b87d
Reviewed-on: https://gerrit.libreoffice.org/43403
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>
Tested-by: Julien Nabet <serval2412@yahoo.fr>
diff --git a/sd/source/core/sdpage.cxx b/sd/source/core/sdpage.cxx
index e1d8193..9a4a74b 100644
--- a/sd/source/core/sdpage.cxx
+++ b/sd/source/core/sdpage.cxx
@@ -128,10 +128,7 @@ SdPage::SdPage(SdDrawDocument& rNewDoc, bool bMasterPage)
    // The name of the layout of the page is used by SVDRAW to determine the
    // presentation template of the outline objects. Therefore, it already
    // contains the designator for the outline (STR_LAYOUT_OUTLINE).
    OUStringBuffer aBuf(SdResId(STR_LAYOUT_DEFAULT_NAME));
    aBuf.append(SD_LT_SEPARATOR).append(STR_LAYOUT_OUTLINE);
    maLayoutName = aBuf.makeStringAndClear();

    maLayoutName = SdResId(STR_LAYOUT_DEFAULT_NAME)+ SD_LT_SEPARATOR STR_LAYOUT_OUTLINE;
    Size aPageSize(GetSize());

    if (aPageSize.Width() > aPageSize.Height())