Lua: remove new warning added by cjson header
Lua: remove new warning added by cjson header

clang doesn't like "extern inline" when no definition
is given right away.

darksideofthemoo/redis-histogram,MSOpenTech/redis,MSOpenTech/redis,HunanTV/redis,spearhead-ea/redis,maodeyi/redis_lua,HunanTV/redis,splitice/redis,HunanTV/redis,splitice/redis,ksarch-saas/redis,slfs007/mk-redis,HunanTV/redis,splitice/redis,maodeyi/redis_lua,himoca/redis,jxwr/redis,ramonsnir/redis,ramonsnir/redis,ttuna/msot-redis,ramonsnir/redis,MSOpenTech/redis,himoca/redis,xuzhezhaozhao/redis_reading,xuzhezhaozhao/redis_reading,ksarch-saas/redis,louisliangjun/redis,darksideofthemoo/redis-histogram,ttuna/msot-redis,slfs007/mk-redis,MSOpenTech/redis,louisliangjun/redis,spearhead-ea/redis,maodeyi/redis_lua,louisliangjun/redis,ksarch-saas/redis,darksideofthemoo/redis-histogram,ttuna/msot-redis,xuzhezhaozhao/redis_reading,MSOpenTech/redis,ttuna/msot-redis,xuzhezhaozhao/redis_reading,spearhead-ea/redis,louisliangjun/redis,himoca/redis,jxwr/redis,ksarch-saas/redis,darksideofthemoo/redis-histogram,splitice/redis,slfs007/mk-redis,jxwr/redis,ttuna/msot-redis