Make all libcurl related options use .nf (no fill) for the SYNOPSIS
section - for consistent look. roffit then renders that section using
<pre> (monospace font) in html for the website.
Extended manpage-syntax (test 1173) with a basic check for it.
Closes#8062
As these two options provide identical functionality, the former for
SOCK5 proxies and the latter for HTTP proxies, merged the two options
together.
As such CURLOPT_SOCKS5_GSSAPI_SERVICE is marked as deprecated as of
7.49.0.
