BUILD: ssl: add USE_ENGINE and disable the openssl engine by default
The OpenSSL engine API is deprecated starting with OpenSSL 3.0.
In order to have a clean build this feature is now disabled by default.
It can be reactivated with USE_ENGINE=1 on the build line.
diff --git a/Makefile b/Makefile
index 0c511bc..726f28f 100644
--- a/Makefile
+++ b/Makefile
@@ -32,6 +32,7 @@
# 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_ENGINE : enable use of OpenSSL Engine.
# USE_LUA : enable Lua support.
# USE_ACCEPT4 : enable use of accept4() on linux. Automatic.
# USE_CLOSEFROM : enable use of closefrom() on *bsd, solaris. Automatic.