[NTG-context] Simplefonts + Linux Libertine fails to do italics and bold

[John Haltiwanger]

The following shows a problem I am seeing when trying to use the
opentype version of Linux Libertine with the simplefonts module.

\usemodule[simplefonts]
\setmainfont[linlibertineo]

\starttext
	Well, {\em this} doesn't work but {\sc this} does... and bold {\bf neither}
\stoptext

Using a recent minimals and a luatex ~0.60.2 .