json: Print to stderr and abort() instead of returning NULL and faulting.

json: Print to stderr and abort() instead of returning NULL and faulting.

No one who uses the JSON API is checking for return values.
Instead of littering the json code with if-else chains,
we will error on any memory allocation failure. Even though
incredibly unlikely malloc will return NULL it's easier to
check for it and print an error instead of faulting.

Signed-off-by: Scott Bauer <scott.bauer@intel.com>