Add deterministic option and use it for the docwiki

It doesn't do anything yet.

IkiWiki.pm

@@ -566,6 +566,14 @@ sub getsetup () {
 		safe => 1,
 		rebuild => 1,
 	},
+	deterministic => {
+		type => "boolean",
+		default => 0,
+		description => "try harder to produce deterministic output",
+		safe => 1,
+		rebuild => 1,
+		advanced => 1,
+	},
 }
 
 sub getlibdirs () {

debian/changelog

@@ -33,6 +33,7 @@ ikiwiki (3.20150330) UNRELEASED; urgency=medium
     release, leading to unstable sorting
   * Sort backlinks deterministically, by falling back to sorting by href
     if the link text is identical
+  * Add a $config{deterministic} option and use it for the docwiki
 
  -- Joey Hess <id@joeyh.name>  Tue, 28 Apr 2015 12:24:08 -0400
 

docwiki.setup

@@ -33,4 +33,5 @@ use IkiWiki::Setup::Standard {
 	disable_plugins => [qw{recentchanges openid}],
 	rcs => $rcs,
 	gitorigin_branch => '', # don't pull during build
+	deterministic => 1,
 }