core: fix compilation with autotools on FreeBSD 12.0

ChangeLog.adoc

@@ -58,6 +58,7 @@ Tests::
 
 Build::
 
+  * core: fix compilation with autotools on FreeBSD 12.0
   * debian: disable Javascript plugin on Debian Buster/Bullseye (issue #1374)
   * python: compile with Python 3 by default
   * python: use pkg-config to detect Python (issue #1382)

src/core/hook/wee-hook-timer.h

@@ -21,6 +21,7 @@
 #define WEECHAT_HOOK_TIMER_H
 
 #include <time.h>
+#include <sys/time.h>
 
 struct t_weechat_plugin;
 struct t_infolist_item;