[bash] statically define __fzf_list_hosts() with either method

When bash-completion (and thus `_known_hosts_real()`) is / is not available this
will typically not change during the lifetime of a shell.

The only exception is if the user would unset `_known_hosts_real()`, but well,
that would be his problem.

So we can easily define `__fzf_list_hosts()` either using `_known_hosts_real()`
or using the old code, and avoid checking every time whether
`_known_hosts_real()` is defined.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>

shell/completion.bash

@@ -411,24 +411,26 @@ _fzf_proc_completion_post() {
 # The function is expected to print hostnames, one per line as well as in the
 # desired sorting and with any duplicates removed, to standard output.
 if ! declare -F __fzf_list_hosts > /dev/null; then
-  __fzf_list_hosts() {
-    if declare -F _known_hosts_real > /dev/null; then
-      # if available, use bash-completions’s _known_hosts_real() for getting the list of hosts
+  if declare -F _known_hosts_real > /dev/null; then
+    # if available, use bash-completions’s _known_hosts_real() for getting the list of hosts
 
+    __fzf_list_hosts() {
       # set the local attribute for any non-local variable that is set by _known_hosts_real()
       local COMPREPLY=()
 
       _known_hosts_real ''
       printf '%s\n' "${COMPREPLY[@]}" | command sort -u --version-sort
-    else
-      # otherwise, get a list of hosts on our own
+    }
+  else
+    # otherwise, get a list of hosts on our own
 
+    __fzf_list_hosts() {
       command cat <(command tail -n +1 ~/.ssh/config ~/.ssh/config.d/* /etc/ssh/ssh_config 2> /dev/null | command grep -i '^\s*host\(name\)\? ' | command awk '{for (i = 2; i <= NF; i++) print $1 " " $i}' | command grep -v '[*?%]') \
         <(command grep -oE '^[[a-z0-9.,:-]+' ~/.ssh/known_hosts 2> /dev/null | command tr ',' '\n' | command tr -d '[' | command awk '{ print $1 " " $1 }') \
         <(command grep -v '^\s*\(#\|$\)' /etc/hosts 2> /dev/null | command grep -Fv '0.0.0.0') |
         command awk '{if (length($2) > 0) {print $2}}' | command sort -u
-    fi
-  }
+    }
+  fi
 fi
 
 _fzf_host_completion() {