gnupg: Fix gpgsm linking for gnupg 2.1.14

gnupg 2.1.14 fails to compile under OS X due to a missing -lintl flag [1].
This was fixed in commit c49c43d7 in the gnupg repository [2], which adds
the flag to Makefile.am.

This commit adds the flag to Makefile.in.

[1] https://lists.gnupg.org/pipermail/gnupg-devel/2016-July/031354.html
[2] https://lists.gnupg.org/pipermail/gnupg-devel/2016-July/031362.html

Fixes #17617.

pkgs/tools/security/gnupg/21.nix

@@ -27,6 +27,8 @@ stdenv.mkDerivation rec {
     readline libusb gnutls adns openldap zlib bzip2
   ];
 
+  patches = [ ./fix-gpgsm-linking.patch ];
+
   postPatch = stdenv.lib.optionalString stdenv.isLinux ''
     sed -i 's,"libpcsclite\.so[^"]*","${pcsclite}/lib/libpcsclite.so",g' scd/scdaemon.c
   ''; #" fix Emacs syntax highlighting :-(

pkgs/tools/security/gnupg/fix-gpgsm-linking.patch

@@ -0,0 +1,11 @@
+--- a/tests/gpgscm/Makefile.in
++++ b/tests/gpgscm/Makefile.in
+@@ -457,7 +457,7 @@
+ 	scheme-config.h opdefines.h scheme.c scheme.h scheme-private.h
+ 
+ gpgscm_LDADD = $(LDADD) $(common_libs) \
+-	$(NETLIBS) $(LIBICONV) $(LIBREADLINE) \
++	$(NETLIBS) $(LIBICONV) $(LIBREADLINE) $(LIBINTL) \
+ 	$(LIBGCRYPT_LIBS) $(GPG_ERROR_LIBS)
+ 
+ t_child_SOURCES = t-child.c