Halt rst2man/rst2html on warnings.
Halt rst2man/rst2html on warnings.

We don't allow compiler warnings in the C code, so I don't see any
reason why we should allow warnings in the documentation.

Warnings in the documentation are now build errors.

zhoualbeart/Varnish-Cache,ajasty-cavium/Varnish-Cache,gauthier-delacroix/Varnish-Cache,ajasty-cavium/Varnish-Cache,zhoualbeart/Varnish-Cache,zhoualbeart/Varnish-Cache,franciscovg/Varnish-Cache,gauthier-delacroix/Varnish-Cache,gauthier-delacroix/Varnish-Cache,alarky/varnish-cache-doc-ja,alarky/varnish-cache-doc-ja,alarky/varnish-cache-doc-ja,mrhmouse/Varnish-Cache,franciscovg/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,varnish/Varnish-Cache,gquintard/Varnish-Cache,ajasty-cavium/Varnish-Cache,gquintard/Varnish-Cache,varnish/Varnish-Cache,franciscovg/Varnish-Cache,zhoualbeart/Varnish-Cache,mrhmouse/Varnish-Cache,alarky/varnish-cache-doc-ja,varnish/Varnish-Cache,feld/Varnish-Cache,gquintard/Varnish-Cache,gauthier-delacroix/Varnish-Cache,chrismoulton/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache,mrhmouse/Varnish-Cache,gauthier-delacroix/Varnish-Cache,chrismoulton/Varnish-Cache,chrismoulton/Varnish-Cache,mrhmouse/Varnish-Cache,alarky/varnish-cache-doc-ja,ajasty-cavium/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache,zhoualbeart/Varnish-Cache,chrismoulton/Varnish-Cache,chrismoulton/Varnish-Cache,feld/Varnish-Cache,franciscovg/Varnish-Cache,ajasty-cavium/Varnish-Cache,franciscovg/Varnish-Cache,mrhmouse/Varnish-Cache