Import of CCTZ from GitHub.

PiperOrigin-RevId: 939824929
Change-Id: Ic5ee66ca8df7197dff9107e6290da9eb112b3d79

absl/time/internal/cctz/src/time_zone_format.cc

diff --git a/absl/time/internal/cctz/src/time_zone_format.cc b/absl/time/internal/cctz/src/time_zone_format.cc
index 4c8d2f9..91b4621 100644
--- a/absl/time/internal/cctz/src/time_zone_format.cc
+++ b/absl/time/internal/cctz/src/time_zone_format.cc
@@ -21,7 +21,8 @@
 #endif
 
 #if HAS_STRPTIME
-#if !defined(_XOPEN_SOURCE) && !defined(__FreeBSD__) && !defined(__OpenBSD__)
+#if !defined(_XOPEN_SOURCE) && !defined(__FreeBSD__) && \
+    !defined(__OpenBSD__) && !defined(__APPLE__)
 #define _XOPEN_SOURCE 500  // Exposes definitions for SUSv2 (UNIX 98).
 #endif
 #endif