gh-117376: Make `Py_DECREF` a macro in ceval.c in free-threaded build (#122975)

`Py_DECREF` and `PyStackRef_CLOSE` are now implemented as macros in the
free-threaded build in ceval.c. There are two motivations;

 * MSVC has problems inlining functions in ceval.c in the PGO build.

 * We will want to mark escaping calls in order to spill the stack
   pointer in ceval.c and we will want to do this around `_Py_Dealloc`
   (or `_Py_MergeZeroLocalRefcount` or `_Py_DecRefShared`), not around
   the entire `Py_DECREF` or `PyStackRef_CLOSE` call.