Add arch/encoding metadata to DB + Fetch Arch Linux x86_64

The encoding metadata will be very useful in finding badly decoded man
pages. The package 'arch' is necessary to properly identify which
package was used, which is not obvious now that I'm going to switch more
systems to the (more common) x86_64 arch.

sql/schema.sql

@@ -24,16 +24,18 @@ CREATE TABLE package_versions (
   package  integer   NOT NULL REFERENCES packages(id) ON DELETE CASCADE,
   version  varchar   NOT NULL,
   released date      NOT NULL,
+  arch     varchar,
   UNIQUE(package, version)
 );
 
 CREATE TABLE man (
   package  integer   NOT NULL REFERENCES package_versions(id) ON DELETE CASCADE,
   name     varchar   NOT NULL,
-  section  varchar   NOT NULL,
   filename varchar   NOT NULL,
   locale   varchar,
   hash     bytea     NOT NULL REFERENCES contents(hash),
+  section  varchar   NOT NULL,
+  encoding varchar,
   UNIQUE(package, filename)
 );
 

sql/update-2016-11-06.sql

@@ -0,0 +1,2 @@
+ALTER TABLE package_versions ADD COLUMN arch varchar;
+ALTER TABLE man ADD COLUMN encoding varchar;