libcontainer: nsenter: nsexec.c: fix warnings
libcontainer: nsenter: nsexec.c: fix warnings

Fix the following warnings when building runc with gcc 6+:

Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:
In function ‘nsexec’:
Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:322:6:
warning: ‘__s’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
      pr_perror("Failed to open %s", ns);
Godeps/_workspace/src/github.com/opencontainers/runc/libcontainer/nsenter/nsexec.c:273:30:
note: ‘__s’ was declared here
 static struct nsenter_config process_nl_attributes(int pipenum, char
*data, int data_size)
                              ^~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Antonio Murdaca <f9809039ea4850e75dcb8d80b778844aa463358f@redhat.com>

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