cmd/testwrapper: apply results of all unit tests to coverage for all …

…packages

This allows coverage from tests that hit multiple packages at once
to be reflected in all those packages' coverage.

Updates #cleanup

Signed-off-by: Percy Wegmann <percy@tailscale.com>

cmd/testwrapper/testwrapper.go

@@ -278,6 +278,7 @@ func main() {
 				goTestArgsWithCoverage,
 				fmt.Sprintf("-coverprofile=%v", coverageFile),
 				"-covermode=set",
+				"-coverpkg=./...",
 			)
 		}