MINOR: ssl: deduplicate ca-file

Typically server line like:
'server-template srv 1-1000 *:443 ssl ca-file ca-certificates.crt'
load ca-certificates.crt 1000 times and stay duplicated in memory.
Same case for bind line: ca-file is loaded for each certificate.
Same 'ca-file' can be load one time only and stay deduplicated in
memory.

As a corollary, this will prevent file access for ca-file when
updating a certificate via CLI.
2 files changed