don't loop forever if pcx has short read

Change-Id: I638792417924bcb8e48995f4e789f84a2cbf4757
(cherry picked from commit c9ba7a2a)
Reviewed-on: https://gerrit.libreoffice.org/17157Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>

filter/source/graphicfilter/ipcx/ipcx.cxx

@@ -224,7 +224,7 @@ void PCXReader::ImplReadBody(BitmapWriteAccess * pAcc)
     nCount = 0;
     for ( ny = 0; ny < nHeight; ny++ )
     {
-        if (m_rPCX.GetError() || m_rPCX.IsEof())
+        if (!m_rPCX.good())
         {
             nStatus = false;
             break;
@@ -248,7 +248,7 @@ void PCXReader::ImplReadBody(BitmapWriteAccess * pAcc)
                     nx--;
                     nCount--;
                 }
-                while ( nx > 0 )
+                while (nx > 0 && m_rPCX.good())
                 {
                     m_rPCX.ReadUChar( nDat );
                     if ( ( nDat & 0xc0 ) == 0xc0 )