Import of CCTZ from GitHub.

PiperOrigin-RevId: 463153060
Change-Id: I6d24915c52bfe6507864df30aad99ba4fea2ea68
diff --git a/absl/time/internal/cctz/src/time_zone_format.cc b/absl/time/internal/cctz/src/time_zone_format.cc
index d8cb047..2e5f532 100644
--- a/absl/time/internal/cctz/src/time_zone_format.cc
+++ b/absl/time/internal/cctz/src/time_zone_format.cc
@@ -19,7 +19,7 @@
 #endif
 
 #if defined(HAS_STRPTIME) && HAS_STRPTIME
-#if !defined(_XOPEN_SOURCE)
+#if !defined(_XOPEN_SOURCE) && !defined(__OpenBSD__)
 #define _XOPEN_SOURCE  // Definedness suffices for strptime.
 #endif
 #endif