driver: Be resilient to KSH_ARRAYS being set in the calling scope

The «emulate» call isn't sufficient, since these lines are parsed before
it takes effect.

Fixes #689 (née #622).

See also #688 for preventing these gymnastics from being needed in the
first place.

See also https://github.com/junegunn/fzf/pull/1924 for an inter-plugin
interaction that this probably fixes.

zsh-syntax-highlighting.zsh

@@ -86,12 +86,12 @@ _zsh_highlight()
   # Before we 'emulate -L', save the user's options
   local -A zsyh_user_options
   if zmodload -e zsh/parameter; then
-    zsyh_user_options=("${(@kv)options}")
+    zsyh_user_options=("${(kv)options[@]}")
   else
     local canonical_options onoff option raw_options
     raw_options=(${(f)"$(emulate -R zsh; set -o)"})
     canonical_options=(${${${(M)raw_options:#*off}%% *}#no} ${${(M)raw_options:#*on}%% *})
-    for option in $canonical_options; do
+    for option in "${canonical_options[@]}"; do
       [[ -o $option ]]
       # This variable cannot be eliminated c.f. workers/42101.
       onoff=${${=:-off on}[2-$?]}