tinycbor: new package

Concise Binary Object Representation (CBOR) Library

Signed-off-by: Fabrice Fontaine <fabrice.fontaine@orange.com>
[Thomas:
 - use lower-case letters in the Config.in option prompt
 - remove BR2_PACKAGE_TINYCBOR_JSON2CBOR sub-option, simply rely on
   the cjson package being enabled
 - pass prefix=/usr only at install time.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>