Fix int overflow on 32 bits systems (#59)

Fix #58

Signed-off-by: Robert-André Mauchin <zebob.m@gmail.com>
diff --git a/bytesource/bytesource_test.go b/bytesource/bytesource_test.go
index 609cf5e..e1a8f54 100644
--- a/bytesource/bytesource_test.go
+++ b/bytesource/bytesource_test.go
@@ -91,9 +91,9 @@
 
 	r := rand.New(New(data))
 
-	got := []int{r.Int(), r.Int(), r.Int(), r.Int(), r.Int()}
+	got := []int64{r.Int63(), r.Int63(), r.Int63(), r.Int63(), r.Int63()}
 
-	want := []int{
+	want := []int64{
 		3568552425102051206,
 		3568552489526560135,
 		3568569467532292485,
diff --git a/fuzz_test.go b/fuzz_test.go
index 6188c2b..d4a9279 100644
--- a/fuzz_test.go
+++ b/fuzz_test.go
@@ -632,10 +632,10 @@
 
 	input := []byte{1, 2, 3}
 
-	var got int
+	var got int64
 	NewFromGoFuzz(input).Fuzz(&got)
 
-	if want := 5563767293437588600; want != got {
+	if want := int64(5563767293437588600); want != got {
 		t.Errorf("Fuzz(%q) = %d, want: %d", input, got, want)
 	}
 }