I'd like to bump the *trusted* clang compiler also,
since the really old trusted clang compiler seems to crash
if we pair old clang with new libcxx. (So the merge will
probably have to bump the trusted clang compiler to
a newer rev).

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4026
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/898693002