Fix implicit declaration of function 'prctl' in installd.

Change-Id: I469ee15a0a8a79d005b15aad5097b6c13c20ab7e
diff --git a/cmds/installd/installd.c b/cmds/installd/installd.c
index e072d0d..35fba42 100644
--- a/cmds/installd/installd.c
+++ b/cmds/installd/installd.c
@@ -15,7 +15,7 @@
 */
 
 #include <sys/capability.h>
-#include <linux/prctl.h>
+#include <sys/prctl.h>
 #include <selinux/android.h>
 #include <selinux/avc.h>