Added some inclusions of string.h where necessary.

diff --git a/server/atom.c b/server/atom.c
index 55fc6b7..63be7b4 100644
--- a/server/atom.c
+++ b/server/atom.c
@@ -8,6 +8,7 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "unicode.h"
 #include "request.h"