Test: wait for actual startup in start_server.
Test: wait for actual startup in start_server.

start_server now uses return value from Tcl exec to get the server pid,
however this introduces errors that depend from timing: a lot of the
testing code base assumed the server to be actually up and running when
server_start returns.

So the old code that waits to see the pid in the log file was restored.

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