On amd64, the real time is reduced from 176.76s to 140.26s.
On ARM, the real time is reduced from 921.61s to 726.30s.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/101580043
Add nacl.bash, the NaCl version of all.bash.
It's a separate script because it builds a variant of package syscall
with a large zip file embedded in it, containing all the input files
needed for tests.
Disable various tests new since the last round, mostly the ones using os/exec.
Fixes#7945.
LGTM=dave
R=golang-codereviews, remyoudompheng, dave, bradfitz
CC=golang-codereviews
https://golang.org/cl/100590044