comphelper: Fix typos

Change-Id: Ia016a20bb36104e18c90ee78c87a3c5fec56af20
Reviewed-on: https://gerrit.libreoffice.org/9134
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>