merge branch 'pr-1836'
merge branch 'pr-1836'

  Add osusergo flag to static build

LGTMs: 2665d0b6daa6ccd1337288f8885cbc52b5d5ee7e@cyphar
Closes #1836

kolyshkin/runc,mYmNeo/runc,rhatdan/runc,xiaochenshen/runc,dqminh/runc,justincormack/runc,estesp/runc,opencontainers/runc,laijs/runc,justincormack/runc,adrianreber/runc,kolyshkin/runc,laijs/runc,opencontainers/runc,mheon/runc,dqminh/runc,mikebrow/runc,mheon/runc,laijs/runc,xiaochenshen/runc,kolyshkin/runc,cyphar/runc,cyphar/runc,mYmNeo/runc,opencontainers/runc,mheon/runc,dqminh/runc,xiaochenshen/runc,estesp/runc,cyphar/runc,estesp/runc,rhatdan/runc,adrianreber/runc,crosbymichael/runc,mYmNeo/runc,justincormack/runc,crosbymichael/runc,crosbymichael/runc,rhatdan/runc,opencontainers/runc,mikebrow/runc,dqminh/runc,adrianreber/runc,kolyshkin/runc,rhatdan/runc,mikebrow/runc