Fix building with --disable-nls

[pacho2]

We are applying this patch in Gentoo for years without issues

Thanks

From 0f8700f022c9917336919b35a93883a660144516 Mon Sep 17 00:00:00 2001
From: Gilles Dartiguelongue <eva@gentoo.org>
Date: Mon, 17 Oct 2016 00:07:59 +0200
Subject: [PATCH] Fix compilation with --disable-nls

---
 src/i18n.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/i18n.h b/src/i18n.h
index c8134a7..efce469 100644
--- a/src/i18n.h
+++ b/src/i18n.h
@@ -31,6 +31,17 @@
 	#include <libintl.h>
 	#include <glib/gi18n.h>
 #else /* NLS is disabled */
+	// In certain environments, some standard headers like <iomanip>
+	// and <locale> include libintl.h. If libintl.h is included after
+	// gettext macros below are defined, it causes a syntax error
+	// at the declaration of the gettext function in libintl.h.
+	//
+	// Fix this by including such a header before defining the macro.
+	//
+	// Note that libintl.h cannot be included directly since in the
+	// ENABLE_NLS=0 case it cannot be assumed that gettext is installed.
+	#include <locale>
+
 	#define _(String) (String)
 	#define N_(String) (String)
 	#define textdomain(String) (String)
-- 
2.10.0