gl2ps-print.cc: Avoid integer overflow in multiplication. * libinterp/corefcn/gl2ps-print.cc (gl2ps_renderer::draw_image, gl2ps_renderer::draw_pixels): Cast integer size argument of OCTAVE_LOCAL_BUFFER to size_t before multiplication to avoid integer overflow. The overflow is very unlikely to happen. But it's an easy fix that doesn't clutter the code too much.