sw/source/core/text/itrcrsr.cxx:1632

SwTxtSizeInfo aSizeInf( GetInfo(), &rText, nCurrStart )

where nCurrStart is non 0 and the hidden 4th argument to SwTxtSizeInfo is
COMPLETE_STRING

in the past it was STRING_LEN unsigned 16bit 0xFFFF and so in GetMinLen in
sw/source/core/text/inftxt.cxx adding x to it resulted in x-1 which at least is
in bounds if selected by the std::min

Change-Id: I78f176804b79fb3c991677adb016579eabcfd56f