Add calls for SELinux MAC checks in keystore.

Add call to SELinux in the has_permission function call. Add
mapping of permission to string used by SELinux. The SELinux
rules currently mirror those currently defined in
keystore.cpp.

Change-Id: I3893a25c50b24396b4198ec8b949eee045987ae8
diff --git a/keystore/Android.mk b/keystore/Android.mk
index 47b7e84..22bba01 100644
--- a/keystore/Android.mk
+++ b/keystore/Android.mk
@@ -28,7 +28,8 @@
 	libkeystore_binder \
 	liblog \
 	libsoftkeymaster \
-	libutils
+	libutils \
+	libselinux
 LOCAL_MODULE := keystore
 LOCAL_MODULE_TAGS := optional
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk