Include to define uid_t.

Change-Id: I02d36346fc3c6236bd64309798b434405f8dfef7
diff --git a/include/cutils/multiuser.h b/include/cutils/multiuser.h
index 191d80c..22bb032 100644
--- a/include/cutils/multiuser.h
+++ b/include/cutils/multiuser.h
@@ -17,6 +17,8 @@
 #ifndef __CUTILS_MULTIUSER_H
 #define __CUTILS_MULTIUSER_H
 
+#include <sys/types.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif