bpo-46008: Move Py*State init into distinct functions.

Include/cpython/pystate.h

@@ -77,6 +77,12 @@ struct _ts {
     struct _ts *next;
     PyInterpreterState *interp;
 
+    /* Has been initialized to a safe state.
+
+       In order to be effective, this must be set to 0 during or right
+       after allocation. */
+    int _initialized;
+
     int recursion_remaining;
     int recursion_limit;
     int recursion_headroom; /* Allow 50 more calls to handle any errors. */

Include/internal/pycore_interp.h

@@ -240,7 +240,6 @@ struct _is {
     struct _is *next;
 
     struct pythreads {
-        int _preallocated_used;
         uint64_t next_unique_id;
         struct _ts *head;
         /* Used in Modules/_threadmodule.c. */
@@ -262,6 +261,11 @@ struct _is {
     int requires_idref;
     PyThread_type_lock id_mutex;
 
+    /* Has been initialized to a safe state.
+
+       In order to be effective, this must be set to 0 during or right
+       after allocation. */
+    int _initialized;
     int finalizing;
 
     struct _ceval_state ceval;

Include/internal/pycore_runtime.h

@@ -67,6 +67,12 @@ struct _Py_unicode_runtime_ids {
 /* Full Python runtime state */
 
 typedef struct pyruntimestate {
+    /* Has been initialized to a safe state.
+
+       In order to be effective, this must be set to 0 during or right
+       after allocation. */
+    int _initialized;
+
     /* Is running Py_PreInitialize()? */
     int preinitializing;
 
@@ -136,9 +142,18 @@ typedef struct pyruntimestate {
 } _PyRuntimeState;
 
 #define _PyRuntimeState_INIT \
-    {.preinitialized = 0, .core_initialized = 0, .initialized = 0}
+    { \
+        ._initialized = 0, \
+    }
 /* Note: _PyRuntimeState_INIT sets other fields to 0/NULL */
 
+static inline void
+_PyRuntimeState_reset(_PyRuntimeState *runtime)
+{
+    /* Make it match _PyRuntimeState_INIT. */
+    memset(runtime, 0, sizeof(*runtime));
+}
+
 
 PyAPI_DATA(_PyRuntimeState) _PyRuntime;