zsh_completion: drop -w, add -S to _arguments
From the docs: http://zsh.sourceforge.net/Doc/Release/Completion-System.html
_arguments -w: "allow option stacking even if one or more of the options take
arguments", so something like "-xy xarg yarg". Mercurial's command line parser
doesn't support that, so the flag got removed in zsh 92584634d3d3 and
bf8b61182043.
_arguments -S: "do not complete options after a ‘--’ appearing on the line". By
options it means things like "-x" and "--foo", but it will still complete
arguments like files.
Differential Revision: https://phab.mercurial-scm.org/D4262
#if no-windows no-osx
$ mkdir -p xdgconf/hg
$ echo '[ui]' > xdgconf/hg/hgrc
$ echo 'username = foobar' >> xdgconf/hg/hgrc
$ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
$ unset HGRCPATH
$ hg config ui.username 2>/dev/null
foobar
#endif