ninja: extract update_* to external update file

srcpkgs/ninja/template

@@ -6,8 +6,6 @@ hostmakedepends="python asciidoc git"
 short_desc="Small build system with a focus on speed"
 maintainer="Juan RP <xtraeme@gmail.com>"
 license="Apache-2.0"
-update_site="https://github.com/martine/ninja/tags"
-update_pattern='archive/v\K[\d.]+(?=\.tar\.gz)'
 homepage="http://martine.github.io/ninja/"
 
 do_fetch() {

srcpkgs/ninja/update

@@ -0,0 +1,2 @@
+site="https://github.com/martine/ninja/tags"
+pattern='archive/v\K[\d.]+(?=\.tar\.gz)'