treewide: Get rid of // comments, even inside comments.

treewide: Get rid of // comments, even inside comments.

Just a style fix.

With this patch, the following reports no hits:

git ls-files | grep '\.[ch]$' | grep -vE 'datapath|sflow' \
    | xargs grep -n // | grep -vE "http|s/|'|\""

Acked-by: Ilya Maximets <i.maximets@samsung.com>
Reported-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>