Remove CM_ONESHOT-specific logic in flock failure checks

Now that we're in a subshell and acting asynchronously, this doesn't do
anything different.

clipmenud

@@ -125,14 +125,8 @@ while true; do
 
     {
     if ! flock -x -w "$lock_timeout" "$lock_fd"; then
-        if (( CM_ONESHOT )); then
         printf 'ERROR: %s\n' 'Timed out waiting for lock' >&2
         exit 1
-        else
-            printf 'ERROR: %s\n' \
-                'Timed out waiting for lock, skipping this run' >&2
-            continue
-        fi
     fi
 
     for selection in clipboard primary; do