BUILD: ssl: unbreak the build with newer libressl

In LibreSSL 3.5.0, BIO is going to become opaque, so haproxy's
compat macros will no longer work. The functions they substitute
have been available since LibreSSL 2.7.0.

(cherry picked from commit d1a2e2b0d1da0dff726738343fbaed044fb93470)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit ca0b6e08dcc3686794d37e8bfcc4e4a4b2adb806)
Signed-off-by: Willy Tarreau <w@1wt.eu>
1 file changed