Most of our code base uses space after comma but not before;
fix the remaining uses before adding a syntax check.

* src/nwfilter/nwfilter_ebiptables_driver.c: Consistently use
commas.
* src/nwfilter/nwfilter_gentech_driver.c: Likewise.
* src/nwfilter/nwfilter_learnipaddr.c: Likewise.
* src/conf/nwfilter_conf.c: Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>