cmd/compile: tweak inliners handling of coverage counter updates

This patch fixes up a bug in the inliner's special case code for
coverage counter updates, which was not properly working for
-covermode=atomic compilations.

Updates #56044.

Change-Id: I9e309312b123121c3df02862623bdbab1f6c6a4b
Reviewed-on: https://go-review.googlesource.com/c/go/+/441858
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

src/runtime/coverage/emitdata_test.go

@@ -406,6 +406,13 @@ func TestApisOnNocoverBinary(t *testing.T) {
 }
 
 func TestIssue56006EmitDataRaceCoverRunningGoroutine(t *testing.T) {
+	if testing.Short() {
+		t.Skipf("skipping test: too long for short mode")
+	}
+	if !goexperiment.CoverageRedesign {
+		t.Skipf("skipping new coverage tests (experiment not enabled)")
+	}
+
 	// This test requires "go test -race -cover", meaning that we need
 	// go build, go run, and "-race" support.
 	testenv.MustHaveGoRun(t)