create appendCopy method in OUStringBuffer

so we can avoid temporary copies when appending a substring of an
OUString to the buffer. I would have preferred to call the method just
"append" but that results in ambiguous method errors when the callsite
is something like
   sal_Int32 n;
   OUStringBuffer s;
   s.append(n, 10);
I'm not sure why

Change-Id: I6b5b6641fcb5b26ce2269f89ef06e03c0b6aa76f
Reviewed-on: https://gerrit.libreoffice.org/58666
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 1 insertions, 1 deletions

diff --git a/writerfilter/source/rtftok/rtfdocumentimpl.cxx b/writerfilter/source/rtftok/rtfdocumentimpl.cxx
index a1afc2bc93a6..60c7b3a3d475 100644
--- a/writerfilter/source/rtftok/rtfdocumentimpl.cxx
+++ b/writerfilter/source/rtftok/rtfdocumentimpl.cxx
@@ -2204,7 +2204,7 @@ RTFError RTFDocumentImpl::popState()
                                                   - aState.aLevelNumbers.size()));
                         }
                         else
-                            aBuf.append(aOrig.copy(i, 1));
+                            aBuf.appendCopy(aOrig, i, 1);
                     }
 
                     pValue->setString(aBuf.makeStringAndClear());