BUILD: Makefile: add USE_QUIC_OPENSSL_COMPAT to make help

Add the missing USE_QUIC_OPENSSL_COMPAT option to `make help`.

No backport needed.

(cherry picked from commit 17bfc75974a8660c43efe71dd80f5351bcf6e341)
Signed-off-by: William Lallemand <wlallemand@haproxy.org>
diff --git a/Makefile b/Makefile
index 8fafee6..cba3fbe 100644
--- a/Makefile
+++ b/Makefile
@@ -35,6 +35,7 @@
 #   USE_OPENSSL          : enable use of OpenSSL. Recommended, but see below.
 #   USE_OPENSSL_WOLFSSL  : enable use of wolfSSL with the OpenSSL API
 #   USE_QUIC             : enable use of QUIC with the quictls API (quictls, libressl, boringssl)
+#   USE_QUIC_OPENSSL_COMPAT : enable use of QUIC with the standard openssl API (limited features)
 #   USE_ENGINE           : enable use of OpenSSL Engine.
 #   USE_LUA              : enable Lua support.
 #   USE_ACCEPT4          : enable use of accept4() on linux. Automatic.