cmd/dist: use GO_TEST_SHORT value more consistently

There were two places where the -short flag was added in order to
speed up tests when run in short mode, in CL 178399 and CL 177417.

It appears viable to re-use the GO_TEST_SHORT value so that -short
flag is not used when the tests are executed on a longtest builder,
where it is not a goal to skip slow tests for improved performance.

Do so, in order to make the testing configurations simpler and more
predictable.

Factor out the flag name out of the string returned by short, so that
it can be used in context of 'go test' which can accept a -short flag,
and a test binary which requires the use of a longer -test.short flag.

For #39054.
For #29252.

Change-Id: I52dfbef73cc8307735c52e2ebaa609305fb05933
Reviewed-on: https://go-review.googlesource.com/c/go/+/233898
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

0 files changed, 0 insertions, 0 deletions