devel/arcanist-lib: Use Mozilla root CA bundle

This fixes problems with Let's Encrypt certificates after
the R3 Let's Encrypt intermediate CA expired.

Arcanist uses its own certificate bundle by default (default.pem),
overriding curl's default, unless curl.cainfo is set explicitly.

The port now replaces this custom bundle with a symlink to Mozilla's
root CA bundle as installed by security/ca_root_nss.

PR: 258824
Reported by: yasu