[3.12] gh-110549: Remove unused includes of <stddef.h> in _testcapi (GH-110552).

sobolevn · serhiy-storchaka · commit 891e276b44f6 · 2023-10-09T14:02:37.000+03:00
(cherry picked from commit 89df5b7) Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
diff --git a/Modules/_testcapi/abstract.c b/Modules/_testcapi/abstract.c
@@ -1,5 +1,3 @@
-#include <stddef.h>               // ptrdiff_t
-
 #define PY_SSIZE_T_CLEAN
 #include "parts.h"
 #include "util.h"
diff --git a/Modules/_testcapi/dict.c b/Modules/_testcapi/dict.c
@@ -1,5 +1,3 @@
-#include <stddef.h>               // ptrdiff_t
-
 #define PY_SSIZE_T_CLEAN
 #include "parts.h"
 #include "util.h"
diff --git a/Modules/_testcapi/set.c b/Modules/_testcapi/set.c
@@ -1,5 +1,3 @@
-#include <stddef.h>               // ptrdiff_t
-
 #include "parts.h"
 #include "util.h"
 
