hwpfilter: remove write-only variable

Change-Id: I03e29b1a3761fcafc70168b04d788dbf3e1584eb
diff --git a/hwpfilter/source/hwpreader.cxx b/hwpfilter/source/hwpreader.cxx
index b4bf35e..9d5a331 100644
--- a/hwpfilter/source/hwpreader.cxx
+++ b/hwpfilter/source/hwpreader.cxx
@@ -3676,7 +3676,6 @@ void HwpReader::makeFormula(TxtBox * hbox)
{
    char mybuf[3000];
    HWPPara* pPar;
    CharShape *cshape = nullptr;

    int n, c, res;
     hchar dest[3];
@@ -3688,8 +3687,6 @@ void HwpReader::makeFormula(TxtBox * hbox)
        for( n = 0; n < pPar->nch && pPar->hhstr[n]->hh;
            n += pPar->hhstr[n]->WSize() )
        {
            if (!cshape)
                cshape = pPar->GetCharShape(n);
            if (l >= sizeof(mybuf)-7)
                break;
            res = hcharconv(pPar->hhstr[n]->hh, dest, UNICODE);