Add missing includes.

Test: Builds.
Change-Id: Ia8b79154902503cdd774dc3b4523466123b4324c
diff --git a/file.cpp b/file.cpp
index d5bb7fe..2f4a517 100644
--- a/file.cpp
+++ b/file.cpp
@@ -22,6 +22,7 @@
 #include <libgen.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>