pull-filter: ignore leading "spaces" in option names

pull-filter: ignore leading "spaces" in option names

It seems sometimes comma-separated pulled options have
an offending leading space. Not sure whether that is an error,
but the change here matches the behaviour of option parsing.

v2: fix typo in commit message
v3: space() --> isspace()

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20221130105502.662374-1-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25582.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>