BUILD: Makefile: add the USE_QUIC option to make help

Add the missing "USE_QUIC" option to `make help`.

Must be backported as far as 2.4.

(cherry picked from commit 1b5f9de1b42d43cdd269690328fbb33875c93a8c)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 96a095499119afa83b51916abe83276bfeeec44a)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 4aa7dbbb950ade96226b075a2180d6097d027f88)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit aea67c1cdee1bdba1fe11a09663e331fdf551d83)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/Makefile b/Makefile
index 05067bc..b70e51e 100644
--- a/Makefile
+++ b/Makefile
@@ -34,6 +34,7 @@
 #   USE_CRYPT_H          : set it if your system requires including crypt.h
 #   USE_GETADDRINFO      : use getaddrinfo() to resolve IPv6 host names.
 #   USE_OPENSSL          : enable use of OpenSSL. Recommended, but see below.
+#   USE_QUIC             : enable use of QUIC with the quictls API (quictls, libressl, boringssl)
 #   USE_LUA              : enable Lua support.
 #   USE_FUTEX            : enable use of futex on kernel 2.6. Automatic.
 #   USE_ACCEPT4          : enable use of accept4() on linux. Automatic.