[tlbuild] Missing includes for zlib when building woff2 (dvisvgm)

[Martin Gieseking]

Hello Mojca,

> However this fails when building dvisvgm's built-in dependency woff2.
> When configuring dvisvgm itself the zlib is found and the flags seem
> to be there, but they don't seem to propagate all the way down to
> woff2.

I'm not sure if I understand the problem correctly. Does woff2 require 
zlib in your build environment? That would be strange because woff2 uses 
the brotli compression library and doesn't rely on zlib. Actually, I 
can't find any reference to zlib in the subset of the woff2 sources 
bundled with dvisvgm. Could you send me a build log with the 
corresponding error messages?

Best,
Martin