*: modernize codebase with newer syntax / helpers (#4110)

Changes came from running
https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/modernize
on the codebase.

pkg/proc/proc_unix_test.go

@@ -56,7 +56,7 @@ func TestIssue419(t *testing.T) {
 		errChan <- grp.Continue()
 	})
 
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		err := <-errChan
 
 		t.Logf("error %T %#v\n", err, err)