Fix memory leak in add_option() for option 'connection'

Fix memory leak in add_option() for option 'connection'

This patch ensures that if an error occurs while processing
the 'connection' directive of an options specification,
the variable 'struct options sub', which is initialized
with init_options(), is properly freed with uninit_options().

Signed-off-by: Guido Vranken <guidovranken@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <CAO5O-E+HdfHNAK=--55054AB374U-Ky4q_-3M114makfPdSnBw@mail.gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14764.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit d89e14d92623731d2fa6343a11072caab32e13cd)