max and min operators in draw_round_box (was: Lilypond not rendering PDF on Mac)

[Tyler Mitchell]

On Wed, Jan 09, 2019 at 12:27:13PM +0000, Stephen Wilkinson wrote:
> [...] it seems to be a struggle to get the postscript file to
> open in anything at all.

I looked at this and it seems the culprit is the draw_round_box
procedure which uses 'max' and 'min' operators, which are not part
of standard PostScript, but are available in Ghostscript:

https://en.wikibooks.org/wiki/PostScript_FAQ#Where_are_min_and_max_functions?

Adding this to the PostScript output (before draw_round_box is
defined) makes it double-clickable in OS X:

 /min { 2 copy gt { exch } if pop } bind def
 /max { 2 copy lt { exch } if pop } bind def


Is it possible to include these in music-drawing-routines.ps so
that the .ps output could be processed with non-Ghostscript
interpreters?

Cheers,
Tyler