concat of OUStringBuffer

[Stephan Bergmann]

On 10/10/2016 10:24 PM, Eike Rathke wrote:
> I'd rather say it's a bug when assigning the involved OUStringBuffer
> (here aLCIDString) to itself again.. so for clarification:
>
> https://gerrit.libreoffice.org/#/c/28666/5 had
>
>     aLCIDString = "[$-" + aLCIDString + "]";
>     aFormatStr.insert( nPosInsertLCID, aLCIDString.toString() );
>
> which produced an erroneous "[$-[$-[$-0]"

Ouch.  Would probably make sense to forbid that O[U]StringBuffer takes 
part in such concatenations (by removing the 
ToStringHelper<O[U]StringBfufer> specializations, which are luckily 
LIBO_INTERNAL_ONLY).  I'll look into that.