BUG/MINOR: ssl: Stop passing dynamic strings as format arguments

gcc complains rightfully:

src/ssl_sock.c: In function ‘ssl_load_global_issuers_from_path’:
src/ssl_sock.c:9860:4: warning: format not a string literal and no format arguments [-Wformat-security]
    ha_warning(warn);
    ^

Introduced in 70df7bf19cebd5593c0abb01923e6c9f72961da6.
1 file changed