Add missing strings include for BSD

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@3119 65c4cc65-6c06-0410-ace0-fbb531ad65f3

utils.c

@@ -10,6 +10,7 @@
  */
 
 #include <ctype.h>
+#include <string.h>
 #include <asterisk/lock.h>
 #include <asterisk/utils.h>