Do some extra checking for the presence of timer_create().

configure.ac

@@ -42,6 +42,7 @@ AC_CHECK_FUNCS([memset])
 AC_CHECK_FUNCS([munmap])
 AC_CHECK_FUNCS([strchr])
 AC_CHECK_FUNCS([strdup])
+AC_CHECK_FUNCS([timer_create])
 AC_CHECK_HEADERS([fcntl.h])
 AC_FUNC_MALLOC
 AC_FUNC_MMAP

src/vmod_file.c

@@ -39,6 +39,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
+#include <time.h>
 #include <stdio.h>
 
 #include "cache/cache.h"
@@ -49,6 +50,10 @@
 
 #include "vcc_file_if.h"
 
+#if ! defined(HAVE_TIMER_CREATE) || ! HAVE_TIMER_CREATE
+#error "timer_create() not found"
+#endif
+
 // varnish-cache pre 7f28888779fd14f99eb34e50f6fb07ea6bbff999
 #ifndef NO_VXID
 #define NO_VXID (0U)