package/armadillo: fix download URL

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/armadillo/armadillo.mk

@@ -5,7 +5,9 @@
 ################################################################################
 
 ARMADILLO_VERSION = 6.500.4
-ARMADILLO_SITE = http://downloads.sourceforge.net/project/arma
+# upstream removed tarball from
+# http://downloads.sourceforge.net/project/arma
+ARMADILLO_SITE = https://ftp.fau.de/macports/distfiles/armadillo
 ARMADILLO_DEPENDENCIES = clapack
 ARMADILLO_INSTALL_STAGING = YES
 ARMADILLO_LICENSE = MPL-2.0