Move missing.h to shared directory
diff --git a/libkmod/libkmod-signature.c b/libkmod/libkmod-signature.c
index 28f993e..8fe5b40 100644
--- a/libkmod/libkmod-signature.c
+++ b/libkmod/libkmod-signature.c
@@ -24,8 +24,9 @@
 #include <string.h>
 #include <stdio.h>
 
+#include <shared/missing.h>
+
 #include "libkmod-internal.h"
-#include "missing.h"
 
 /* These types and tables were copied from the 3.7 kernel sources.
  * As this is just description of the signature format, it should not be