lib-index: mail_index_alloc_cache_get() now allows mailbox_path=NULL. Also did a small code cleanup with this change.
lib-index: mail_index_alloc_cache_get() now allows mailbox_path=NULL.
Also did a small code cleanup with this change.

--HG--
branch : HEAD

dscho/dovecot,dscho/dovecot,dscho/dovecot,dscho/dovecot,dscho/dovecot