* make json-c mandatory according to [0]
* make libubootenv mandatory according to [1]
* drop local patch that has been upstreamed [2]
* libconfig is not mandatory anymore if no lua parser is enabled
* adjust Config.in comment according to json-c and libubootenv
[0]: 82e7532244
[1]: 75838874e2
[2]: 1999685830
Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>