buildroot

jsmn: new package

Signed-off-by: David Bachelart <david.bachelart@bbright.com>
[Thomas:
 - fix license, it's MIT, not BSD
 - use TARGET_CONFIGURE_OPTS instead of manually passing CC and AR
 - use full destination path
 - keep only sha256 hash
 - rewrap Config.in help text]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>