add SO_PRIORITY (closes #19802)

Patch by Claudiu Popa.

Misc/NEWS

@@ -18,6 +18,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #19802: Add socket.SO_PRIORITY.
+
 - Issue #11508: Fixed uuid.getnode() and uuid.uuid1() on environment with
   virtual interface.  Original patch by Kent Frazier.
 

Modules/socketmodule.c

@@ -6241,6 +6241,9 @@ PyInit__socket(void)
 #ifdef  SO_BINDTODEVICE
     PyModule_AddIntMacro(m, SO_BINDTODEVICE);
 #endif
+#ifdef  SO_PRIORITY
+    PyModule_AddIntMacro(m, SO_PRIORITY);
+#endif
 
     /* Maximum number of connections for "listen" */
 #ifdef  SOMAXCONN