std.Build: implement unit test timeouts

For now, there is a flag to `zig build` called `--test-timeout-ms` which
accepts a value in milliseconds. If the execution time of any individual
unit test exceeds that number of milliseconds, the test is terminated
and marked as timed out.

In the future, we may want to increase the granularity of this feature
by allowing timeouts to be specified per-step or even per-test. However,
a global option is actually very useful. In particular, it can be used
in CI scripts to ensure that no individual unit test exceeds some
reasonable limit (e.g. 60 seconds) without having to assign limits to
every individual test step in the build script.

Also, individual unit test durations are now shown in the time report
web interface -- this was fairly trivial to add since we're timing tests
(to check for timeouts) anyway.

This commit makes progress on #19821, but does not close it, because
that proposal includes a more sophisticated mechanism for setting
timeouts.

Co-Authored-By: David Rubin <david@vortan.dev>

0 files changed, 0 insertions, 0 deletions