Fix -loadbalancing parsing when used as the final option

[w1boost1889M]

Summary

Fix command-line parsing of the -loadbalancing encoder option when it is placed at the end of the argument list.

Problem

-loadbalancing consumes one value, but its argument availability check currently requires two remaining arguments:

(n + 1 < argc)

As a result, a valid final argument pair such as:

-loadbalancing 0

is silently ignored, leaving the default load-balancing setting enabled.

Fix

Use the same one-argument availability check as the surrounding single-value options:

(n < argc)