Windows: Fix AsciiDoc / DocBook builds.

The "quotes" section of the Asciidoctor compatibility file appears to
be incompatible with Cygwin's version of AsciiDoc (8.6.3).

Change-Id: Ifd08095effa07bc7277a2fff9de322dda51a8d47
Reviewed-on: https://code.wireshark.org/review/3804
Reviewed-by: Gerald Combs <gerald@wireshark.org>