dev-lang/go: Add covdata to tools directory

With the go 1.22.3 upgrade, the covdata tool is required for our builds
to succeed. Specifically, the sys-apps/policymanager ebuild fails in the
test phase because it tries to check test coverage. This succeeded
before by coincidence because there were no test files present, and the
covdata tool did not actually get invoked in go 1.20 when no test files
were present. The 1.20 output would have looked like this:

>>> Test phase: sys-apps/policymanager-9999
 * Running Policy Manager unit tests ...
?   	policy-manager	[no test files]
?   	policy-manager/cmd/getstatus	[no test files]
?   	policy-manager/cmd/monitor	[no test files]
?   	policy-manager/cmd/showconfig	[no test files]
?   	policy-manager/protos	[no test files]
?   	policy-manager/third_party/chromium/devicepolicyproto	[no test files]

However, with go 1.22, covdata gets invoked regardless of whether or not
test files are present, crashing the build. The change is documented
here: https://tip.golang.org/doc/go1.22#tools. Specifically, the
coverage for packages with no test files is no longer undefined, but is
instead calculated to be 0%.

BUG=b/342019096
TEST=presubmit, run `go tool covdata` and validate that covdata is
present
RELEASE_NOTE=None

Change-Id: I28cdaff17c70f109bef93215ce2c58e39d990ce8
Reviewed-on: https://cos-review.googlesource.com/c/third_party/overlays/chromiumos-overlay/+/72896
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
2 files changed