syscall: StartProcess Chroot and Credential.
syscall: StartProcess Chroot and Credential.

R=rsc, iant, agl1
CC=golang-dev
http://codereview.appspot.com/4280065

Committer: Adam Langley <db68fba232b2c49ed3e9d3081df349dde7b61dfd@golang.org>

gnanderson/go,apparentlymart/golang,apparentlymart/golang,tv42/old-go,ssrl/go,apparentlymart/golang,ssrl/go,pombredanne/go-deleteme,tv42/old-go,ssrl/go,dsriram/golang,ssrl/go,pombredanne/go-deleteme,gnanderson/go,tv42/old-go,dsriram/golang,tv42/old-go,apparentlymart/golang,gnanderson/go,ssrl/go,pombredanne/go-deleteme,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,gnanderson/go,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,dsriram/golang,apparentlymart/golang,tv42/old-go,apparentlymart/golang,tv42/old-go,ssrl/go,dsriram/golang,gnanderson/go,dsriram/golang,pombredanne/go-deleteme,ssrl/go,apparentlymart/golang,gnanderson/go,dsriram/golang