BUILD: ssl: fix typo in HAVE_SSL_CTX_ADD_SERVER_CUSTOM_EXT macro

HAVE_SSL_CTX_ADD_SERVER_CUSTOM_EXT was introduced in ec609098718b9c1cd803ca57442b2b98c9ba4a16
however it was defined as HAVE_SL_CTX_ADD_SERVER_CUSTOM_EXT (missing "S")
let us fix typo
diff --git a/include/haproxy/openssl-compat.h b/include/haproxy/openssl-compat.h
index b4af429..3fe58be 100644
--- a/include/haproxy/openssl-compat.h
+++ b/include/haproxy/openssl-compat.h
@@ -50,7 +50,7 @@
 #endif
 
 #if ((OPENSSL_VERSION_NUMBER >= 0x1000200fL) && !defined(OPENSSL_NO_TLSEXT) && !defined(LIBRESSL_VERSION_NUMBER) && !defined(OPENSSL_IS_BORINGSSL))
-#define HAVE_SL_CTX_ADD_SERVER_CUSTOM_EXT
+#define HAVE_SSL_CTX_ADD_SERVER_CUSTOM_EXT
 #endif
 
 #if ((OPENSSL_VERSION_NUMBER >= 0x10002000L) && !defined(LIBRESSL_VERSION_NUMBER))
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index ccce578..f2c8a66 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -1497,7 +1497,7 @@
 #endif
 
 
-#ifdef HAVE_SL_CTX_ADD_SERVER_CUSTOM_EXT
+#ifdef HAVE_SSL_CTX_ADD_SERVER_CUSTOM_EXT
 
 #define CT_EXTENSION_TYPE 18
 
@@ -3217,7 +3217,7 @@
 	}
 #endif
 
-#ifdef HAVE_SL_CTX_ADD_SERVER_CUSTOM_EXT
+#ifdef HAVE_SSL_CTX_ADD_SERVER_CUSTOM_EXT
 	if (sctl_ex_index >= 0 && ckch->sctl) {
 		if (ssl_sock_load_sctl(ctx, ckch->sctl) < 0) {
 			memprintf(err, "%s '%s.sctl' is present but cannot be read or parsed'.\n",