Backport rev. 51971:

Fix %zd string formatting on Mac OS X so it prints negative numbers.

In addition to testing positive numbers, verify negative numbers work in configure.
In order to avoid compiler warnings on OS X 10.4, also change the order of the check
for the format character to use (PY_FORMAT_SIZE_T) in the sprintf format
for Py_ssize_t.  This patch changes PY_FORMAT_SIZE_T from "" to "l" if it wasn't
defined at configure time.  Need to verify the buildbot results.
diff --git a/Include/pyport.h b/Include/pyport.h
index be6c51f..8f8e514 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -126,7 +126,7 @@
  * Py_ssize_t on the platform.
  */
 #ifndef PY_FORMAT_SIZE_T
-#   if SIZEOF_SIZE_T == SIZEOF_INT
+#   if SIZEOF_SIZE_T == SIZEOF_INT && !defined(__APPLE__)
 #       define PY_FORMAT_SIZE_T ""
 #   elif SIZEOF_SIZE_T == SIZEOF_LONG
 #       define PY_FORMAT_SIZE_T "l"