Tweak clang-format config for PyObject_HEAD macros

Summary: Unfortunately those macros are designed in a way where they don't require a ';' after use, which confuses clang-format unless we manually add them to the `StatementMacros` list in the clang-format config.

Based on Facebook D21689198

.clang-format

···
 DerivePointerAlignment: false
 PointerAlignment: Left
 IncludeBlocks: Regroup
+StatementMacros: [PyObject_HEAD, PyObject_VAR_HEAD, _PyObject_HEAD_EXTRA]
 IncludeCategories:
   # C system headers
   - Regex:           '^<.*\.h?>'

capi/cpython-types.h

···
 #endif
 
 typedef struct _object {
-  _PyObject_HEAD_EXTRA Py_ssize_t ob_refcnt;
+  _PyObject_HEAD_EXTRA
+  Py_ssize_t ob_refcnt;
 } PyObject;
 
 typedef struct {
···
 typedef struct PyMethodDef PyMethodDef;
 
 typedef struct PyModuleDef_Base {
-  PyObject_HEAD PyObject* (*m_init)(void);
+  PyObject_HEAD
+  PyObject* (*m_init)(void);
   Py_ssize_t m_index;
   PyObject* m_copy;
 } PyModuleDef_Base;

ext/Modules/gcmodule-test.cpp

···
 
 TEST_F(GcModuleExtensionApiTest, NewReturnsAllocatedObject) {
   struct BarObject {
-    PyObject_HEAD int value;
+    PyObject_HEAD
+    int value;
   };
   destructor dealloc = [](PyObject* self) {
     PyTypeObject* type = Py_TYPE(self);
···
 
 TEST_F(GcModuleExtensionApiTest, NewVarReturnsAllocatedObject) {
   struct BarObject {
-    PyObject_HEAD int value;
+    PyObject_HEAD
+    int value;
   };
   struct BarContainer {
-    PyObject_VAR_HEAD BarObject* items[1];
+    PyObject_VAR_HEAD
+    BarObject* items[1];
   };
   destructor dealloc = [](PyObject* self) {
     PyTypeObject* type = Py_TYPE(self);

ext/Objects/object-test.cpp

···
 
 TEST_F(ObjectExtensionApiTest, NewReturnsAllocatedObject) {
   struct BarObject {
-    PyObject_HEAD int value;
+    PyObject_HEAD
+    int value;
   };
   PyType_Slot slots[] = {
       {0, nullptr},
···
 
 TEST_F(ObjectExtensionApiTest, NewVarReturnsAllocatedObject) {
   struct BarObject {
-    PyObject_HEAD int value;
+    PyObject_HEAD
+    int value;
   };
   struct BarContainer {
-    PyObject_VAR_HEAD BarObject* items[1];
+    PyObject_VAR_HEAD
+    BarObject* items[1];
   };
   PyType_Slot slots[] = {
       {0, nullptr},

ext/Objects/typeobject-test.cpp

···
 }
 
 TEST_F(TypeExtensionApiTest, CallExtensionTypeReturnsExtensionInstancePyro) {
-  // clang-format off
   struct BarObject {
     PyObject_HEAD
     int value;
   };
-  // clang-format on
   newfunc new_func = [](PyTypeObject* type, PyObject*, PyObject*) {
     void* slot = PyType_GetSlot(type, Py_tp_alloc);
     return reinterpret_cast<allocfunc>(slot)(type, 0);
···
 }
 
 TEST_F(TypeExtensionApiTest, GenericNewReturnsExtensionInstance) {
-  // clang-format off
   struct BarObject {
     PyObject_HEAD
   };
-  // clang-format on
   PyType_Slot slots[] = {
       {Py_tp_alloc, reinterpret_cast<void*>(PyType_GenericAlloc)},
       {Py_tp_new, reinterpret_cast<void*>(PyType_GenericNew)},
···
 typedef void (*verifyfunc)(PyObject*);
 static verifyfunc createBarTypeWithMembers() {
   struct BarObject {
-    PyObject_HEAD char t_bool;
+    PyObject_HEAD
+    char t_bool;
     char t_byte;
     unsigned char t_ubyte;
     short t_short;
···
 }
 
 TEST_F(TypeExtensionApiTest, MemberStringWithNullReturnsNone) {
-  // clang-format off
   struct BarObject {
     PyObject_HEAD
     char* name;
   };
-  // clang-format on
   static const PyMemberDef members[] = {
       {"name", T_STRING, offsetof(BarObject, name), 0, nullptr},
       {nullptr},
···
 // TODO(T56634824): Figure out why Pyro differs from CPython.
 TEST_F(TypeExtensionApiTest, MemberUnknownRaisesSystemErrorPyro) {
   int unknown_type = -1;
-  // clang-format off
   struct BarObject {
     PyObject_HEAD
     int value;
   };
-  // clang-format on
   static const PyMemberDef members[] = {
       {"value", unknown_type, offsetof(BarObject, value), 0, nullptr},
       {nullptr},
···
 
 static void createBarTypeWithGetSetObject() {
   struct BarObject {
-    PyObject_HEAD long attribute;
+    PyObject_HEAD
+    long attribute;
     long readonly_attribute;
   };
 
···
 }
 
 TEST_F(TypeExtensionApiTest, FromSpecWithoutDeallocInheritsDefaultDealloc) {
-  // clang-format off
   struct FooObject {
     PyObject_HEAD
   };
-  // clang-format on
   static PyType_Slot slots[1];
   slots[0] = {0, nullptr};
   static PyType_Spec spec;
···
 }
 
 TEST_F(TypeExtensionApiTest, DefaultDeallocCallsDelAndFinalize) {
-  // clang-format off
   struct FooObject {
     PyObject_HEAD
   };
-  // clang-format on
   destructor del_func = [](PyObject*) {
     moduleSet("__main__", "called_del", Py_True);
   };
···
 }
 
 TEST_F(TypeExtensionApiTest, FromSpecWithBasesSubclassInheritsParentDealloc) {
-  // clang-format off
   struct FooObject {
     PyObject_HEAD
   };
   struct FooSubclassObject {
     FooObject base;
   };
-  // clang-format on
   destructor dealloc_func = [](PyObject* self) {
     PyTypeObject* tp = Py_TYPE(self);
     PyObject_Del(self);
···
 }
 
 TEST_F(TypeExtensionApiTest, FromSpecWithBasesSubclassInheritsDefaultDealloc) {
-  // clang-format off
   struct FooObject {
     PyObject_HEAD
   };
   struct FooSubclassObject {
     FooObject base;
   };
-  // clang-format on
   static PyType_Slot base_slots[1];
   base_slots[0] = {0, nullptr};
   static PyType_Spec base_spec;
···
   PyObjectPtr foo_type(mainModuleGet("Foo"));
 
   struct FooObject {
-    PyObject_HEAD PyObject* dict;
+    PyObject_HEAD
+    PyObject* dict;
     int t_int;
   };
   static PyMemberDef members[2];