Portability fixes.

diff --git a/configure.ac b/configure.ac
index 506c3f5..98c767e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -950,6 +950,7 @@
 	getprotobynumber \
 	getpwuid \
 	getservbyport \
+	gettimeofday \
 	inet_network \
 	lseek64 \
 	lstat \