sandbox: Add host filesystem

This allows reading of files from the host filesystem in sandbox.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@ti.com>
diff --git a/Makefile b/Makefile
index fc18dd4..8f01ff4 100644
--- a/Makefile
+++ b/Makefile
@@ -264,6 +264,7 @@
 	fs/fdos/libfdos.o \
 	fs/jffs2/libjffs2.o \
 	fs/reiserfs/libreiserfs.o \
+	fs/sandbox/libsandboxfs.o \
 	fs/ubifs/libubifs.o \
 	fs/yaffs2/libyaffs2.o \
 	fs/zfs/libzfs.o