Implement C API function PySet_Discard.

Author: fangerer

graalpython/com.oracle.graal.python.cext/src/setobject.c

@@ -67,3 +67,8 @@ UPCALL_ID(PySet_Pop);
 PyObject * PySet_Pop(PyObject *set) {
     return UPCALL_CEXT_O(_jls_PySet_Pop, native_to_java(set));
 }
+
+UPCALL_ID(PySet_Discard);
+int PySet_Discard(PyObject *set, PyObject *key) {
+    return UPCALL_CEXT_I(_jls_PySet_Discard, native_to_java(set), native_to_java(key));
+}

graalpython/lib-graalpython/python_cext.py

@@ -234,6 +234,14 @@ def PyFrozenSet_New(iterable):
         return frozenset()
 
 
+@may_raise(-1)
+def PySet_Discard(s, key):
+    if key in s:
+        s.discard(key)
+        return 1
+    return 0
+
+
 ##################### MAPPINGPROXY