There's no reason to not have the mounts linked list init also in the info
struct, rather than provide as a paramater to lws_create_vhost().  Now
is a good time to normalize that since this api only exists in master.

This also allows oldstyle "do everything at context creation time in one
vhost" guys to leverage mounts.

Also there's no reason the mounts linked-list pointer and all uses in lws
are non-const, so make them all explicitly const *.

Update the info struct docs to clarify which members are used when creating
a vhost and which for context creation.

Signed-off-by: Andy Green <andy@warmcat.com>