Fix stat_unix_test on FreeBSD

This splits out the platform-specific parts to stat_linux_test.go and
stat_freebsd_test.go.

Signed-off-by: Doug Rabson <dfr@rabson.org>

pkg/system/stat_freebsd_test.go

@@ -0,0 +1,19 @@
+//go:build freebsd
+// +build freebsd
+
+package system
+
+import (
+	"syscall"
+	"testing"
+)
+
+// TestFromStatT tests fromStatT for a tempfile
+func platformTestFromStatT(t *testing.T, stat *syscall.Stat_t, s *StatT) {
+	if stat.Mode != uint16(s.Mode()) {
+		t.Fatal("got invalid mode")
+	}
+	if stat.Mtimespec != s.Mtim() {
+		t.Fatal("got invalid mtim")
+	}
+}

pkg/system/stat_linux_test.go

@@ -0,0 +1,19 @@
+//go:build linux
+// +build linux
+
+package system
+
+import (
+	"syscall"
+	"testing"
+)
+
+// TestFromStatT tests fromStatT for a tempfile
+func platformTestFromStatT(t *testing.T, stat *syscall.Stat_t, s *StatT) {
+	if stat.Mode != s.Mode() {
+		t.Fatal("got invalid mode")
+	}
+	if stat.Mtim != s.Mtim() {
+		t.Fatal("got invalid mtim")
+	}
+}

pkg/system/stat_unix_test.go

@@ -22,9 +22,6 @@ func TestFromStatT(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if stat.Mode != s.Mode() {
-		t.Fatal("got invalid mode")
-	}
 	if stat.Uid != s.UID() {
 		t.Fatal("got invalid uid")
 	}
@@ -34,7 +31,7 @@ func TestFromStatT(t *testing.T) {
 	if stat.Rdev != s.Rdev() {
 		t.Fatal("got invalid rdev")
 	}
-	if stat.Mtim != s.Mtim() {
-		t.Fatal("got invalid mtim")
-	}
+	// Types for Mode can vary and not all platforms have an Mtim
+	// member in Stat_t
+	platformTestFromStatT(t, stat, s)
 }