Disable recursive watchdog signal handler
Disable recursive watchdog signal handler

If we are in the signal handler, we don't want to handle
the signal again.  In extreme cases, this can cause a stack overflow
and segfault Redis.

Fixes #1771

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