Replace search.cpan.org with metacpan.org

search.cpan.org has been EOL'd, with metacpan.org being the official
replacement to which URLs now redirect.  Update links to match the new
URL. Also update links to CPAN to use https as it will redirect from
http.

Author: Daniel Gustafsson
Discussion: https://postgr.es/m/B74C0219-6BA9-46E1-A524-5B9E8CD3BDB3@yesql.se

Author: michaelpq

doc/src/sgml/acronyms.sgml

@@ -71,7 +71,7 @@
     <term><acronym>CPAN</acronym></term>
     <listitem>
      <para>
-      <ulink url="http://www.cpan.org/">Comprehensive Perl Archive Network</ulink>
+      <ulink url="https://www.cpan.org/">Comprehensive Perl Archive Network</ulink>
      </para>
     </listitem>
    </varlistentry>

doc/src/sgml/external-projects.sgml

@@ -65,7 +65,7 @@
       <entry>DBD::Pg</entry>
       <entry>Perl</entry>
       <entry>Perl DBI driver</entry>
-      <entry><ulink url="http://search.cpan.org/dist/DBD-Pg/"></ulink></entry>
+      <entry><ulink url="https://metacpan.org/release/DBD-Pg/"></ulink></entry>
      </row>
 
      <row>

doc/src/sgml/install-windows.sgml

@@ -473,7 +473,7 @@ $ENV{CONFIG}="Debug";
       ActiveState Perl installation, nor in the ActiveState Perl Package
       Manager (PPM) library. To install, download the
       <filename>IPC-Run-&lt;version&gt;.tar.gz</> source archive from CPAN,
-      at <ulink url="http://search.cpan.org/dist/IPC-Run/"></>, and
+      at <ulink url="https://metacpan.org/release/IPC-Run/"></>, and
       uncompress. Edit the <filename>buildenv.pl</> file, and add a PERL5LIB
       variable to point to the <filename>lib</> subdirectory from the
       extracted archive. For example: