vendor/ujson: update ujson to latest (esnme/ultrajson@2f1d487)
vendor/ujson: update ujson to latest (esnme/ultrajson@2f1d487)

ujson has been used GCC __builtin_expect directive. If you want
really fast performance, compile ujson using GCC is better.

Signed-off-by: Koichi Shiraishi <2e5bdfebde234ed3509bcfc18121c70b6631e207@gmail.com>

zchee/deoplete-go,zchee/deoplete-go