https://bugzilla.mozilla.org/show_bug.cgi?id=1812604

Index: ipc/chromium/src/third_party/libevent/bsd/event2/event-config.h
--- ipc/chromium/src/third_party/libevent/bsd/event2/event-config.h.orig
+++ ipc/chromium/src/third_party/libevent/bsd/event2/event-config.h
@@ -512,7 +512,7 @@
 #endif
 
 /* The size of `time_t', as computed by sizeof. */
-#ifdef __LP64__
+#if defined(__LP64__) || defined (__OpenBSD__)
 #define EVENT__SIZEOF_TIME_T 8
 #else
 #define EVENT__SIZEOF_TIME_T 4
