Add QUIC support

ext/openssl/extconf.rb

@@ -176,6 +176,12 @@ def find_openssl_library
 # added in 4.0.0
 have_func("ASN1_BIT_STRING_set1(NULL, NULL, 0, 0)", "openssl/asn1.h")
 
+# QUIC support - requires OpenSSL 3.5.0+, not available in LibreSSL
+if is_openssl && checking_for("OpenSSL version >= 3.5.0") {
+  try_static_assert("OPENSSL_VERSION_NUMBER >= 0x30500000L", "openssl/opensslv.h") }
+  $defs.push("-DHAVE_OSSL_QUIC_CLIENT_METHOD")
+end
+
 Logging::message "=== Checking done. ===\n"
 
 # Append flags from environment variables.

ext/openssl/ossl.h

@@ -78,6 +78,10 @@
 # define OSSL_HAVE_IMMUTABLE_PKEY
 #endif
 
+#if !OSSL_IS_LIBRESSL && defined(HAVE_OSSL_QUIC_CLIENT_METHOD)
+# define OSSL_USE_QUIC
+#endif
+
 /*
  * Common Module
  */