Add TCP_CONGESTION and TCP_USER_TIMEOUT

Issue #26273: Add new socket.TCP_CONGESTION (Linux 2.6.13) and
socket.TCP_USER_TIMEOUT (Linux 2.6.37) constants.

Patch written by Omar Sandoval.
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 7f6cd4d..d5506a6 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -7540,6 +7540,12 @@
 #ifdef  TCP_FASTOPEN
     PyModule_AddIntMacro(m, TCP_FASTOPEN);
 #endif
+#ifdef  TCP_CONGESTION
+    PyModule_AddIntMacro(m, TCP_CONGESTION);
+#endif
+#ifdef  TCP_USER_TIMEOUT
+    PyModule_AddIntMacro(m, TCP_USER_TIMEOUT);
+#endif
 
     /* IPX options */
 #ifdef  IPX_TYPE