BUG/MINOR: ssl/cli: fix "show ssl ca-file <name>" not to mix cli+ssl contexts

BUG/MINOR: ssl/cli: fix "show ssl ca-file <name>" not to mix cli+ssl contexts

The "show ssl ca-file <name>" command mixes some generic pointers from
the "ctx.cli" struct and context-specific ones from "ctx.ssl" while both
are in a union. The i0 integer used to store the current ca_index overlaps
with new_crlfile_entry which is thus harmless for now but is at the mercy
of any reordering or addition of these fields. Let's add dedicated fields
into the ssl structure for this.

Comments were added on top of the affected functions to indicate what they
use.

This needs to be backported to 2.5.