Unify termination signal handling across platforms

- All supported platforms can handle the same set of signals we're
  interested in, thus we don't need build contraints to use a set of
  signals on Linux, while restricting ourselves to only SIGINT on Darwin
  and Windows.
- According to the documentation of os/signal, similar to SIGINT and
  SIGTERM, SIGHUP causes the program to exit, therefore add it to the
  list of handled signals.

Signed-off-by: Rodolfo Carvalho <rcarvalh@redhat.com>

pkg/util/interrupt/interrupt.go

@@ -20,8 +20,13 @@ import (
 	"os"
 	"os/signal"
 	"sync"
+	"syscall"
 )
 
+// terminationSignals are signals that cause the program to exit in the
+// supported platforms (linux, darwin, windows).
+var terminationSignals = []os.Signal{syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT}
+
 // Handler guarantees execution of notifications after a critical section (the function passed
 // to a Run method), even in the presence of process termination. It guarantees exactly once
 // invocation of the provided notify functions.
@@ -82,7 +87,7 @@ func (h *Handler) Signal(s os.Signal) {
 // per Handler instance, so calling Run more than once will not behave as the user expects.
 func (h *Handler) Run(fn func() error) error {
 	ch := make(chan os.Signal, 1)
-	signal.Notify(ch, childSignals...)
+	signal.Notify(ch, terminationSignals...)
 	defer func() {
 		signal.Stop(ch)
 		close(ch)