[libpeas] Fix i18n support by adding back ENABLE_NLS.

[Garrett Regier <gregier src gnome org>]

commit e143c854f197e16e409057755f8117ad32a277f4
Author: Gabor Kelemen <kelemeng gnome hu>
Date:   Wed Apr 2 18:26:56 2014 +0200

    Fix i18n support by adding back ENABLE_NLS.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=727501

 configure.ac |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 89e46df..d14d6ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -70,6 +70,8 @@ dnl Gettext stuff.
 dnl ================================================================
 
 IT_PROG_INTLTOOL([0.40.0])
+AS_IF([test "$USE_NLS" = "yes"],
+      [AC_DEFINE([ENABLE_NLS], [1], [Defined if native language support should be enabled.])])
 
 GETTEXT_PACKAGE=libpeas
 AC_SUBST(GETTEXT_PACKAGE)