[luatex] some bits of opentype math testing

[Arthur Reutenauer]

>                                                       Well, I know it
> is a major source of confusion, but the OpenType specification choose
> to make our life harder by supporting two contradictory file name
> extension schemes!

  I've seen a TrueType-flavoured OpenType font with extension .otf once,
but it's admittedly very rare.

  And the main difference between TrueType- and CFF
(PostScript)-flavoured OpenType fonts is more likely to be in the
hinting engine anyway, not the degree of the Bézier curves.

	Arthur