Use implCopySequence to avoid overhead of non-const operator[]

Change-Id: I1e2385c6c7270f7bac9748a61fbf56e3e4246e1c
Reviewed-on: https://gerrit.libreoffice.org/68621
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
diff --git a/include/comphelper/sequence.hxx b/include/comphelper/sequence.hxx
index 59cd74f..7f13429 100644
--- a/include/comphelper/sequence.hxx
+++ b/include/comphelper/sequence.hxx
@@ -91,10 +91,8 @@ namespace comphelper

        OSL_ENSURE(0 <= _nPos && _nPos < nLength, "invalid index");

        for (sal_Int32 i = _nPos + 1; i < nLength; ++i)
        {
            _rSeq[i-1] = _rSeq[i];
        }
        T* pPos = _rSeq.getArray() + _nPos;
        internal::implCopySequence(pPos + 1, pPos, nLength - _nPos - 1);

        _rSeq.realloc(nLength-1);
    }