Pass arguments in filter_options()

Commit 80f9dff ("Parse -U argument and update internal diff context
state") accidently dropped the passing of arguments, breaking for
example calling tig with branch name as argument.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
Signed-off-by: Jonas Fonseca <fonseca@diku.dk>