Prefer https: URLs

In Gnulib, Emacs, etc. we are changing ftp: and http: URLs to use
https:, to discourage man-in-the-middle attacks when downloading
software. The attached patch propagates these changes upstream to
Automake.  This patch does not affect files that Automake is
downstream of, which I'll patch separately.

Althouth the resources are not secret, plain HTTP is vulnerable to
malicious routers that tamper with responses from GNU servers,
and this sort of thing is all too common when people in some other
countries browse US-based websites. See, for example:

Aceto G, Botta A, Pescapé A, Awan MF, Ahmad T, Qaisar
S. Analyzing internet censorship in Pakistan. RTSI
2016. https://dx.doi.org/10.1109/RTSI.2016.7740626

HTTPS is not a complete solution here, but it can be a significant
help. The GNU project regularly serves up code to users, so we should
take some care here.

8 files changed, 8 insertions, 8 deletions

diff --git a/contrib/check-html.am b/contrib/check-html.am
index fc5db41ae..a12075e1b 100644
--- a/contrib/check-html.am
+++ b/contrib/check-html.am
@@ -12,7 +12,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 ## Makefile.am fragment to produce HTML output from RST-formatted
 ## log files produced by the parallel-tests output.
diff --git a/contrib/multilib/README b/contrib/multilib/README
index 35c726f84..c15d2b539 100644
--- a/contrib/multilib/README
+++ b/contrib/multilib/README
@@ -5,5 +5,5 @@ For a little more information, see:
 
 The master (and probably more up-to-date) copies of the 'config-ml.in'
 and 'symlink-tree' files are maintained in the GCC development tree
-at <http://gcc.gnu.org/svn.html>.  The same is probably true also for
+at <https://gcc.gnu.org/svn.html>.  The same is probably true also for
 the 'multi.m4' file.
diff --git a/contrib/t/help-multilib.sh b/contrib/t/help-multilib.sh
index b58ca80d1..ead697381 100755
--- a/contrib/t/help-multilib.sh
+++ b/contrib/t/help-multilib.sh
@@ -12,7 +12,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Make sure that our macro 'AM_ENABLE_MULTILIB' adds proper text to
 # the configure help screen.
diff --git a/contrib/t/local.mk b/contrib/t/local.mk
index d55fb9583..b5e1b699b 100644
--- a/contrib/t/local.mk
+++ b/contrib/t/local.mk
@@ -13,7 +13,7 @@
 ## GNU General Public License for more details.
 ##
 ## You should have received a copy of the GNU General Public License
-## along with this program.  If not, see <http://www.gnu.org/licenses/>.
+## along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 ## -------------------------------- ##
 ##  Tests for stuff in 'contrib/'.  ##
diff --git a/contrib/t/multilib.sh b/contrib/t/multilib.sh
index 3899ce449..117aa93ff 100755
--- a/contrib/t/multilib.sh
+++ b/contrib/t/multilib.sh
@@ -12,7 +12,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Check multilib support.
 # Based on a test case from Ralf Corsepius.
diff --git a/contrib/t/parallel-tests-html-recursive.sh b/contrib/t/parallel-tests-html-recursive.sh
index f2d1fba08..d664b8d62 100755
--- a/contrib/t/parallel-tests-html-recursive.sh
+++ b/contrib/t/parallel-tests-html-recursive.sh
@@ -12,7 +12,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Recursive use of 'check-html'.  See Automake bug#11287.
 
diff --git a/contrib/t/parallel-tests-html.sh b/contrib/t/parallel-tests-html.sh
index 4d2f8e34e..9576b6232 100755
--- a/contrib/t/parallel-tests-html.sh
+++ b/contrib/t/parallel-tests-html.sh
@@ -12,7 +12,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Check parallel-tests features:
 #  - check-html
diff --git a/contrib/tap-driver.pl b/contrib/tap-driver.pl
index 637c14c3c..d631aba91 100755
--- a/contrib/tap-driver.pl
+++ b/contrib/tap-driver.pl
@@ -12,7 +12,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # As a special exception to the GNU General Public License, if you
 # distribute this file as part of a program that contains a