lua-cjson: use LUA_CJSON_SUBDIR

The infra sets _SUBDIR to the correct value, so we can use it to define
_LICENSE_FILES.

This removes the need for LUA_CJSON_VERSION_UPSTREAM.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/lua-cjson/lua-cjson.mk

@@ -4,9 +4,8 @@
 #
 ################################################################################
 
-LUA_CJSON_VERSION_UPSTREAM = 2.1.0
-LUA_CJSON_VERSION = $(LUA_CJSON_VERSION_UPSTREAM)-1
+LUA_CJSON_VERSION = 2.1.0-1
 LUA_CJSON_LICENSE = MIT
-LUA_CJSON_LICENSE_FILES = lua-cjson-$(LUA_CJSON_VERSION_UPSTREAM)/LICENSE
+LUA_CJSON_LICENSE_FILES = $(LUA_CJSON_SUBDIR)/LICENSE
 
 $(eval $(luarocks-package))