[PATCH] configure: add --without-docs switch

[David Bremner]

mp39590 at gmail.com writes:

> From: Mikhail <mp39590 at gmail.com>
>
> Previously documentation was build automatically if sphinx/doxygen
> executable were found. The switch is used to unconditionally disable
> sphinx/doxygen detection and therefor, building of documentation
> (including man pages).

I pushed this patch, along with some whitespace cleanup.

It exposes one of our tests as broken (one of the subtests of
T010-help); I verified that it was equally broken on systems without
sphinx.

d