maint: Use parentheses around condition for switch(),while(),if() statements. * libinterp/corefcn/dirfns.cc, libinterp/octave-value/ov-fcn-handle.cc, liboctave/array/Sparse.cc, scripts/image/rgb2ind.m, scripts/io/importdata.m, scripts/io/strread.m, scripts/optimization/fminbnd.m, scripts/optimization/sqp.m, scripts/plot/graphics_toolkit.m, scripts/plot/hdl2struct.m, scripts/plot/legend.m, scripts/plot/print.m, scripts/plot/printd.m, scripts/plot/private/__contour__.m, scripts/plot/private/__go_draw_axes__.m, scripts/plot/struct2hdl.m, scripts/polynomial/polyeig.m, scripts/sparse/bicg.m, scripts/specfun/ellipke.m, scripts/special-matrix/gallery.m, scripts/ui/errordlg.m, scripts/ui/helpdlg.m, scripts/ui/inputdlg.m, scripts/ui/listdlg.m, scripts/ui/questdlg.m, scripts/ui/warndlg.m: Use parentheses around condition for switch(),while(),if() statements.

#include <iostream>
#include <octave/oct.h>
#include <octave/octave.h>
#include <octave/parse.h>

int
main (void)
{
  string_vector argv (2);
  argv(0) = "embedded";
  argv(1) = "-q";

  octave_main (2, argv.c_str_vec (), 1);

  octave_idx_type n = 2;
  octave_value_list in;

  for (octave_idx_type i = 0; i < n; i++)  
    in(i) = octave_value (5 * (i + 2));
  
  octave_value_list out = feval ("gcd", in, 1);

  if (!error_state && out.length () > 0)
    std::cout << "GCD of [" 
              << in(0).int_value () 
              << ", " 
              << in(1).int_value ()
              << "] is " << out(0).int_value () 
              << std::endl;
  else
    std::cout << "invalid\n";

  return 0;
}