Update to 0.21

See https://lists.gnu.org/archive/html/bug-gettext/2020-07/msg00035.html
for the applied patch.

Gettext.Tools.nuspec

@@ -2,7 +2,7 @@
 <package xmlns="http://schemas.microsoft.com/packaging/2011/08/nuspec.xsd">
     <metadata>
         <id>Gettext.Tools</id>
-        <version>0.20.2</version>
+        <version>0.21</version>
         <title>GNU gettext tools for Windows</title>
         <authors>Vaclav Slavik</authors>
         <license type="expression">GPL-3.0-or-later</license>

Makefile

@@ -1,5 +1,5 @@
 
-GETTEXT_VERSION   = 0.20.2
+GETTEXT_VERSION   = 0.21
 LIBICONV_VERSION  = 1.16
 
 # version of the gettext-tools-windows package; usually same as GETTEXT_VERSION

patches/gettext-0.21-0001-build-Fix-build-failure-on-mingw-formatstring_ruby.patch

@@ -0,0 +1,24 @@
+From 296c70c182c93c78c59c751db45823012dad5b4e Mon Sep 17 00:00:00 2001
+From: Michele Locati <[email protected]>
+Date: Thu, 30 Jul 2020 18:58:02 +0200
+Subject: [PATCH] build: Fix build failure on mingw (formatstring_ruby)
+
+---
+ gettext-tools/woe32dll/gettextsrc-exports.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/gettext-tools/woe32dll/gettextsrc-exports.c b/gettext-tools/woe32dll/gettextsrc-exports.c
+index 4477ae8d4..6d7608959 100644
+--- a/gettext-tools/woe32dll/gettextsrc-exports.c
++++ b/gettext-tools/woe32dll/gettextsrc-exports.c
+@@ -50,6 +50,7 @@ VARIABLE(formatstring_python)
+ VARIABLE(formatstring_python_brace)
+ VARIABLE(formatstring_qt)
+ VARIABLE(formatstring_qt_plural)
++VARIABLE(formatstring_ruby)
+ VARIABLE(formatstring_scheme)
+ VARIABLE(formatstring_sh)
+ VARIABLE(formatstring_smalltalk)
+-- 
+2.28.0.windows.1
+