fix: use ftpmirror.gnu.org instead of ftp.gnu.org

ftp.gnu.org is unreliable and frequently times out during CI builds.
ftpmirror.gnu.org is GNU's own CDN that auto-redirects to the nearest
mirror. This is the recommended download method per
https://www.gnu.org/prep/ftp.en.html

Also normalizes /pub/gnu/ paths to /gnu/ since ftpmirror only serves
the latter.

Affects: libiconv, gettext, gmp, idn2, libunistring, ncurses, readline

config/artifact/ncurses.yml

@@ -4,5 +4,5 @@ ncurses:
       - COPYING
   source:
     type: filelist
-    url: 'https://ftp.gnu.org/pub/gnu/ncurses/'
+    url: 'https://ftpmirror.gnu.org/gnu/ncurses/'
     regex: '/href="(?<file>ncurses-(?<version>[^"]+)\.tar\.gz)"/'

config/pkg/lib/gettext.yml

@@ -3,7 +3,7 @@ gettext:
   artifact:
     source:
       type: filelist
-      url: 'https://ftp.gnu.org/pub/gnu/gettext/'
+      url: 'https://ftpmirror.gnu.org/gnu/gettext/'
       regex: '/href="(?<file>gettext-(?<version>[^"]+)\.tar\.xz)"/'
     metadata:
       license-files: [gettext-runtime/intl/COPYING.LIB]

config/pkg/lib/gmp.yml

@@ -3,7 +3,7 @@ gmp:
   artifact:
     source:
       type: filelist
-      url: 'https://ftp.gnu.org/gnu/gmp/'
+      url: 'https://ftpmirror.gnu.org/gnu/gmp/'
       regex: '/href="(?<file>gmp-(?<version>[^"]+)\.tar\.xz)"/'
     source-mirror:
       type: url

config/pkg/lib/idn2.yml

@@ -3,7 +3,7 @@ idn2:
   artifact:
     source:
       type: filelist
-      url: 'https://ftp.gnu.org/gnu/libidn/'
+      url: 'https://ftpmirror.gnu.org/gnu/libidn/'
       regex: '/href="(?<file>libidn2-(?<version>[^"]+)\.tar\.gz)"/'
     metadata:
       license-files: [COPYING.LESSERv3]

config/pkg/lib/libiconv.yml

@@ -3,7 +3,7 @@ libiconv:
   artifact:
     source:
       type: filelist
-      url: 'https://ftp.gnu.org/gnu/libiconv/'
+      url: 'https://ftpmirror.gnu.org/gnu/libiconv/'
       regex: '/href="(?<file>libiconv-(?<version>[^"]+)\.tar\.gz)"/'
     metadata:
       license-files: [COPYING.LIB]

config/pkg/lib/libunistring.yml

@@ -3,7 +3,7 @@ libunistring:
   artifact:
     source:
       type: filelist
-      url: 'https://ftp.gnu.org/gnu/libunistring/'
+      url: 'https://ftpmirror.gnu.org/gnu/libunistring/'
       regex: '/href="(?<file>libunistring-(?<version>[^"]+)\.tar\.gz)"/'
     metadata:
       license-files: [COPYING.LIB]

config/pkg/lib/readline.yml

@@ -3,7 +3,7 @@ readline:
   artifact:
     source:
       type: filelist
-      url: 'https://ftp.gnu.org/pub/gnu/readline/'
+      url: 'https://ftpmirror.gnu.org/gnu/readline/'
       regex: '/href="(?<file>readline-(?<version>[^"]+)\.tar\.gz)"/'
     metadata:
       license-files: [COPYING]