Add backward version support on the server side

The server now also supports clients using the previous communication
protocol 4:4 in addition to 4:5.

Protocol 4:5 was introduced with pcsc-lite 2.3.0 in Aug 2024.
Protocol 4:4 was introduced with pcsc-lite 1.8.24 in Oct 2018.

Protocol 4:5 adds the command CMD_GET_READER_EVENTS. This command will
not be used by older clients. They will just work as if the server was
also using protocol version 4:4.

Author: LudovicRousseau

src/winscard_msg.h

@@ -52,6 +52,8 @@ THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define PROTOCOL_VERSION_MINOR 5
 /** Minor version the client also supports */
 #define PROTOCOL_VERSION_MINOR_CLIENT_BACKWARD 4
+/** Minor version the server also supports */
+#define PROTOCOL_VERSION_MINOR_SERVER_BACKWARD 4
 
 	/**
 	 * @brief Information transmitted in \ref CMD_VERSION Messages.

src/winscard_svc.c

@@ -407,7 +407,11 @@ static void * ContextThread(LPVOID newContext)
 						veStr.major, veStr.minor);
 					Log3(PCSC_LOG_ERROR, "Server protocol is %d:%d",
 						PROTOCOL_VERSION_MAJOR, PROTOCOL_VERSION_MINOR);
-					veStr.rv = SCARD_E_SERVICE_STOPPED;
+
+					if (veStr.minor < PROTOCOL_VERSION_MINOR_SERVER_BACKWARD)
+						veStr.rv = SCARD_E_SERVICE_STOPPED;
+					else
+						Log1(PCSC_LOG_INFO, "Enable backward compatibility");
 				}
 
 				/* set the server protocol version */