[NaCl SDK] Build sel_ldr and ncval against debian/stable sysroot
This allows sel_ldr to be deployed and run on debian/stable.
Currently we are building against the host system libraries
which are currently ubuntu/precise. This results in binarys
that depend on more recent versions of glibc than are available
in debian/stable.
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_nacl_sdk;tryserver.chromium.mac:mac_nacl_sdk;tryserver.chromium.win:win_nacl_sdk
Review URL: https://codereview.chromium.org/
1061713005
Cr-Commit-Position: refs/heads/master@{#328219}