gh-106581: Project through calls (#108067)

This finishes the work begun in gh-107760. When, while projecting a superblock, we encounter a call to a short, simple function, the superblock will now enter the function using `_PUSH_FRAME`, continue through it, and leave it using `_POP_FRAME`, and then continue through the original code. Multiple frame pushes and pops are even possible. It is also possible to stop appending to the superblock in the middle of a called function, when running out of space or encountering an unsupported bytecode.

Objects/codeobject.c

@@ -396,6 +396,9 @@ init_code(PyCodeObject *co, struct _PyCodeConstructor *con)
     int nlocals, ncellvars, nfreevars;
     get_localsplus_counts(con->localsplusnames, con->localspluskinds,
                           &nlocals, &ncellvars, &nfreevars);
+    if (con->stacksize == 0) {
+        con->stacksize = 1;
+    }
 
     co->co_filename = Py_NewRef(con->filename);
     co->co_name = Py_NewRef(con->name);