[tlbuild] A strange probem with TL2016 mendex binary

[Akira Kakuto]

Dear Nicola,

> A FreeBSD user in Japan says that the patch does not fix the issue.
> Sorry.

I think that the file texmf-dist/web2c/texmf.cnf lacks
an inevitable variable for mendex.

Please find an entry

% Makeindex style (.ist) files.
INDEXSTYLE = .;$TEXMF/makeindex//

in texmf-dist/web2c/texmf.cnf.
Just below the entry, add two lines:

% mendex dictionary (.dict) files.
INDEXDICTIONARY = .;$TEXMF/makeindex//


After the above change, please test your
example.

If it turns out that it is OK, I will change
texmf.cnf in texmf-dist/web2c and texk/kpathsea.

Best,
Akira