Make sure to only load PyUnicode_AsUTF8AndSize in needed in limited…

… API

We don't use this function unless limited API >= 3.10, but we were
loading it regardless. Usually it's ok in Unix-like systems where Python
just has a single lib that we load from, but in Windows where there is a
separate python3.dll this would not work as the symbol would not have
been exposed in this more limited DLL file. This makes it much clearer
under what condition is this function needed.

src/if_python3.c

@@ -252,10 +252,16 @@ static HINSTANCE hinstPy3 = 0; // Instance of python.dll
 # define PyModule_AddObject py3_PyModule_AddObject
 # define PyImport_AppendInittab py3_PyImport_AppendInittab
 # define PyImport_AddModule py3_PyImport_AddModule
-# if PY_VERSION_HEX >= 0x030300f0
-#  define PyUnicode_AsUTF8AndSize py3_PyUnicode_AsUTF8AndSize
+# ifdef USE_LIMITED_API
+#  if Py_LIMITED_API >= 0x030a0000
+#   define PyUnicode_AsUTF8AndSize py3_PyUnicode_AsUTF8AndSize
+#  endif
 # else
-#  define _PyUnicode_AsString py3__PyUnicode_AsString
+#  if PY_VERSION_HEX >= 0x030300f0
+#   define PyUnicode_AsUTF8AndSize py3_PyUnicode_AsUTF8AndSize
+#  else
+#   define _PyUnicode_AsString py3__PyUnicode_AsString
+#  endif
 # endif
 # undef PyUnicode_CompareWithASCIIString
 # define PyUnicode_CompareWithASCIIString py3_PyUnicode_CompareWithASCIIString
@@ -400,7 +406,8 @@ static PyObject* (*py3_PyDict_GetItemString)(PyObject *, const char *);
 static int (*py3_PyDict_Next)(PyObject *, Py_ssize_t *, PyObject **, PyObject **);
 static PyObject* (*py3_PyLong_FromLong)(long);
 static PyObject* (*py3_PyDict_New)(void);
-# if PY_VERSION_HEX >= 0x03080000
+# if (defined(USE_LIMITED_API) && Py_LIMITED_API >= 0x03080000) || \
+       (!defined(USE_LIMITED_API) && PY_VERSION_HEX >= 0x03080000)
 static int (*py3_PyIter_Check)(PyObject *o);
 # endif
 static PyObject* (*py3_PyIter_Next)(PyObject *);
@@ -446,10 +453,16 @@ static PyObject* py3__Py_FalseStruct;
 static PyObject* py3__Py_TrueStruct;
 static int (*py3_PyModule_AddObject)(PyObject *m, const char *name, PyObject *o);
 static int (*py3_PyImport_AppendInittab)(const char *name, PyObject* (*initfunc)(void));
-# if PY_VERSION_HEX >= 0x030300f0
+# ifdef USE_LIMITED_API
+#  if Py_LIMITED_API >= 0x030a0000
 static char* (*py3_PyUnicode_AsUTF8AndSize)(PyObject *unicode, Py_ssize_t *size);
+#  endif
 # else
+#  if PY_VERSION_HEX >= 0x030300f0
+static char* (*py3_PyUnicode_AsUTF8AndSize)(PyObject *unicode, Py_ssize_t *size);
+#  else
 static char* (*py3__PyUnicode_AsString)(PyObject *unicode);
+#  endif
 # endif
 static int (*py3_PyUnicode_CompareWithASCIIString)(PyObject *unicode, const char* string);
 static PyObject* (*py3_PyUnicode_AsEncodedString)(PyObject *unicode, const char* encoding, const char* errors);
@@ -625,10 +638,16 @@ static struct
     {"PyObject_Init", (PYTHON_PROC*)&py3__PyObject_Init},
     {"PyModule_AddObject", (PYTHON_PROC*)&py3_PyModule_AddObject},
     {"PyImport_AppendInittab", (PYTHON_PROC*)&py3_PyImport_AppendInittab},
-# if PY_VERSION_HEX >= 0x030300f0
+# ifdef USE_LIMITED_API
+#  if Py_LIMITED_API >= 0x030a0000
     {"PyUnicode_AsUTF8AndSize", (PYTHON_PROC*)&py3_PyUnicode_AsUTF8AndSize},
+#  endif
 # else
+#  if PY_VERSION_HEX >= 0x030300f0
+    {"PyUnicode_AsUTF8AndSize", (PYTHON_PROC*)&py3_PyUnicode_AsUTF8AndSize},
+#  else
     {"_PyUnicode_AsString", (PYTHON_PROC*)&py3__PyUnicode_AsString},
+#  endif
 # endif
     {"PyUnicode_CompareWithASCIIString", (PYTHON_PROC*)&py3_PyUnicode_CompareWithASCIIString},
     {"PyUnicode_AsUTF8String", (PYTHON_PROC*)&py3_PyUnicode_AsUTF8String},