gh-112050: Make collections.deque thread-safe in free-threaded builds (#113830)

Use critical sections to make deque methods that operate on mutable 
state thread-safe when the GIL is disabled. This is mostly accomplished
by using the @critical_section Argument Clinic directive, though there
are a few places where this was not possible and critical sections had
to be manually acquired/released.

Author: mpage

Include/internal/pycore_pyatomic_ft_wrappers.h

@@ -20,11 +20,13 @@ extern "C" {
 #endif
 
 #ifdef Py_GIL_DISABLED
+#define FT_ATOMIC_LOAD_SSIZE(value) _Py_atomic_load_ssize(&value)
 #define FT_ATOMIC_LOAD_SSIZE_RELAXED(value) \
     _Py_atomic_load_ssize_relaxed(&value)
 #define FT_ATOMIC_STORE_SSIZE_RELAXED(value, new_value) \
     _Py_atomic_store_ssize_relaxed(&value, new_value)
 #else
+#define FT_ATOMIC_LOAD_SSIZE(value) value
 #define FT_ATOMIC_LOAD_SSIZE_RELAXED(value) value
 #define FT_ATOMIC_STORE_SSIZE_RELAXED(value, new_value) value = new_value
 #endif

Misc/NEWS.d/next/Core and Builtins/2024-01-08-21-57-41.gh-issue-112050.qwgjx1.rst

@@ -0,0 +1 @@
+Make methods on :class:`collections.deque` thread-safe when the GIL is disabled.