Make gnunet-download-manager.scm no longer install.

It was written for a guile version which is no longer supported.
No one of us has really tested it in a very long time to care about
updating it to a supported guile version.
We don't want to install broken scripts, so at this point either
someone steps up and fixes it or it remains bitrotting where it
currently is.

src/fs/Makefile.am

@@ -89,8 +89,9 @@ bin_PROGRAMS = \
   gnunet-fs \
   gnunet-unindex
 
-bin_SCRIPTS = \
-  gnunet-download-manager.scm
+#bin_SCRIPTS = \
+#  gnunet-download-manager.scm
+noinst_SCRIPTS = gnunet-download-manager.scm
 
 gnunet_directory_SOURCES = \
  gnunet-directory.c
@@ -574,6 +575,6 @@ EXTRA_DIST = \
   test_gnunet_service_fs_migration_data.conf \
   test_gnunet_service_fs_p2p_cadet.conf \
   test_pseudonym_data.conf \
-  $(bin_SCRIPTS)
+  $(noinst_SCRIPTS)
 
 CLEANFILES = $(check_SCRIPTS)