Rootfs: reduce redundant parsing of mountinfo
Rootfs: reduce redundant parsing of mountinfo

Postpone parsing mountinfo until pivot_root() actually failed

Signed-off-by: Tatsushi Inagaki <d275e2ddef1ea9d1d5759b035b351061bdc43719@jp.ibm.com>

shishir-a412ed/runc,justincormack/runc,cyphar/runc,stefanberger/runc,avagin/runc,mikebrow/runc,crosbymichael/runc,rhatdan/runc,rajasec/runc,coolljt0725/runc,WeiZhang555/runc,dqminh/runc,mikebrow/runc,rhatdan/runc,jhowardmsft/runc,laijs/runc,dqminh/runc,hqhq/runc,mikebrow/runc,mYmNeo/runc,xiaochenshen/runc,nkwilson/runc,maxamillion/runc,crosbymichael/runc,dqminh/runc,coolljt0725/runc,adrianreber/runc,estesp/runc,estesp/runc,nkwilson/runc,maxamillion/runc,WeiZhang555/runc,laijs/runc,mYmNeo/runc,crosbymichael/runc,cloudfoundry-incubator/runc,rajasec/runc,shishir-a412ed/runc,mheon/runc,justincormack/runc,sunyuan3/runc,nkwilson/runc,kolyshkin/runc,estesp/runc,avagin/runc,keloyang/runc,rajasec/runc,mheon/runc,shishir-a412ed/runc,jhowardmsft/runc,vbatts/runc,opencontainers/runc,justincormack/runc,cyphar/runc,vbatts/runc,keloyang/runc,dqminh/runc,docker/runc,cloudfoundry-incubator/runc,adrianreber/runc,sunyuan3/runc,xiaochenshen/runc,keloyang/runc,rhatdan/runc,vbatts/runc,cyphar/runc,kolyshkin/runc,adrianreber/runc,stefanberger/runc,opencontainers/runc,xiaochenshen/runc,opencontainers/runc,docker/runc,stefanberger/runc,hqhq/runc,coolljt0725/runc,mheon/runc,maxamillion/runc,wking/runc,sunyuan3/runc,wking/runc,cloudfoundry-incubator/runc,kolyshkin/runc,opencontainers/runc,kolyshkin/runc,wking/runc,jhowardmsft/runc,avagin/runc,docker/runc,hqhq/runc,rhatdan/runc,WeiZhang555/runc,mYmNeo/runc,laijs/runc