Improve openssl interactive_check_cert. (closes #3899)

Improve openssl interactive_check_cert. (closes #3899)

Don't use X509_NAME_oneline() with a fixed size buffer, which could
truncate the string, perhaps leaving off the CN field entirely.
Instead, work directly off the X509_NAME.

Rather than use strstr to tokenize it, call
X509_NAME_get_text_by_NID() with the nid types.  Although
X509_NAME_get_text_by_NID() is "legacy", it is the most directly
useful for mutt in this simple interactive prompt.

The function was set up to include the ST and C fields in the prompt,
but the loop limit was too low.  I believe this was an oversight, so
increase the loop to include those two fields.