[metacity] build: use AM_GNU_GETTEXT_REQUIRE_VERSION

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 30cdf2c5b99c4d3b49ba110c830a41e2bb005a32
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Thu Apr 9 15:28:12 2020 +0300

    build: use AM_GNU_GETTEXT_REQUIRE_VERSION

 configure.ac | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 7522434e..044f47f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -69,7 +69,8 @@ dnl Internationalization
 dnl **************************************************************************
 
 AM_GNU_GETTEXT([external])
-AM_GNU_GETTEXT_VERSION([0.19.4])
+AM_GNU_GETTEXT_VERSION([0.19.6])
+AM_GNU_GETTEXT_REQUIRE_VERSION([0.19.6])
 
 GETTEXT_PACKAGE=metacity
 AC_SUBST([GETTEXT_PACKAGE])