The new cjson has some improvements over our current version including
increased platform compatability, a new resource limit to restrict
decode depth, and better invalid number handling.
One minor change was required to deps/Makefile because this version
of cjson doesn't export itself globally, so we added a quick little
define of -DENABLE_CJSON_GLOBAL.
cjson now has an optional higher performing float parsing interface,
but we are not including it (g_fmt.c, dtoa.c) because it requires
endianness declaration during compile time.
This commit is exactly lua_cjson.c from 2.1.0 with one minor
change of altering the two Lua includes for local search
instead of system-wide importing.
