CLEANUP: ssl-sock: use HA_OPENSSL_VERSION_NUMBER instead of OPENSSL_VERSION_NUMBER

Most tests on OPENSSL_VERSION_NUMBER have become complex and break all
the time because this number is fake for some derivatives like LibreSSL.
This patch creates a new macro, HA_OPENSSL_VERSION_NUMBER, which will
carry the real openssl version defining the compatibility level, and
this version will be adjusted depending on the variants.
diff --git a/src/backend.c b/src/backend.c
index 5807a2e..ed3c459 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1583,7 +1583,7 @@
 
 
 #if USE_OPENSSL && (defined(OPENSSL_IS_BORINGSSL) || \
-    ((OPENSSL_VERSION_NUMBER >= 0x10101000L) && !defined(LIBRESSL_VERSION_NUMBER)))
+    ((HA_OPENSSL_VERSION_NUMBER >= 0x10101000L) && !defined(LIBRESSL_VERSION_NUMBER)))
 
 	if (!reuse && cli_conn && srv &&
 	    (srv->ssl_ctx.options & SRV_SSL_O_EARLY_DATA) &&