Issue #5765: Apply a hard recursion limit in the compiler

Previously, excessive nesting in expressions would blow the
stack and segfault the interpreter. Now, a hard limit based
on the configured recursion limit and a hardcoded scaling
factor is applied.

Include/symtable.h

@@ -30,6 +30,8 @@ struct symtable {
     PyObject *st_private;           /* name of current class or NULL */
     PyFutureFeatures *st_future;    /* module's future features that affect
                                        the symbol table */
+    int recursion_depth;            /* current recursion depth */
+    int recursion_limit;            /* recursion limit */
 };
 
 typedef struct _symtable_entry {