lib/ignore: Replace lib/fnmatch with github.com/gobwas/glob

Because it's literally ten times faster:



	benchmark                  old ns/op     new ns/op     delta

	BenchmarkMatch-8           13842         1200          -91.33%

	BenchmarkMatchCached-8     139           147           +5.76%



	benchmark                  old allocs     new allocs     delta

	BenchmarkMatch-8           0              0              +0.00%

	BenchmarkMatchCached-8     0              0              +0.00%



	benchmark                  old bytes     new bytes     delta

	BenchmarkMatch-8           12            0             -100.00%

	BenchmarkMatchCached-8     0             0             +0.00%

lib/ignore/ignore_test.go

@@ -509,3 +509,29 @@ func TestHashOfEmpty(t *testing.T) {
 		t.Error("there are more than zero patterns")
 	}
 }
+
+func TestWindowsPatterns(t *testing.T) {
+	// We should accept patterns as both a/b and a\b and match that against
+	// both kinds of slash as well.
+	if runtime.GOOS != "windows" {
+		t.Skip("Windows specific test")
+		return
+	}
+
+	stignore := `
+	a/b
+	c\d
+	`
+	pats := New(true)
+	err := pats.Parse(bytes.NewBufferString(stignore), ".stignore")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tests := []string{`a\b`, `c\d`}
+	for _, pat := range tests {
+		if !pats.Match(pat) {
+			t.Errorf("Should match %s", pat)
+		}
+	}
+}