add xmake.lua

[waruqi]

please install xmake from the master branch, install doc

build:

$ xmake

run xredis_server:

$ xmake run

build all with benchmark:

$ xmake --all

build only for benchmark:

$ xmake build benchmark

run all benchmark tests:

xmake run benchmark

run the given benchmark test:

xmake run xClient

rebuild:

xmake -r