security/keys/Kconfig: add KEYS_COMPAT option for keyctl tool

The Keyctl tool of Raspbian OS doesn't work because Linux kernel of the rpi3
branch doesn't have compat_key functions.

To solve this problem, KEYS_COMPAT option is added to security/keys/Kconfig
file.

Signed-off-by: Seunghun Han <[email protected]>

Author: kkamagui

security/keys/Kconfig

@@ -20,6 +20,10 @@ config KEYS
 
 	  If you are unsure as to whether this is required, answer N.
 
+config KEYS_COMPAT
+	def_bool y
+	depends on COMPAT && KEYS
+
 config PERSISTENT_KEYRINGS
 	bool "Enable register of persistent per-UID keyrings"
 	depends on KEYS