Added OpenSSL version check. (Currently commented out)

httplib.h

@@ -80,6 +80,10 @@ typedef int socket_t;
 #include <openssl/ssl.h>
 #include <openssl/x509v3.h>
 
+// #if OPENSSL_VERSION_NUMBER < 0x1010100fL
+// #error Sorry, OpenSSL versions prior to 1.1.1 are not supported
+// #endif
+
 #if OPENSSL_VERSION_NUMBER < 0x10100000L
 #include <openssl/crypto.h>
 inline const unsigned char *ASN1_STRING_get0_data(const ASN1_STRING *asn1) {