component/font,fontconfig: make fonts shareable

Instead of the previous approach which relied on a side effect of
installing *-fonts parts that would write in parts/fonts/ and make the
fonts automatically available to applications, use a new approach where
each part is "pure", without side effects.
To make the fonts available to applications, a fontconfig font.conf
listing all the parts with fonts needs to be generated and set as
$FONTCONFIG environment variable.

A template font.conf is included in component/fontconfig

component/fontconfig/buildout.cfg

 [buildout]
 extends =
-  ../fonts/buildout.cfg
   ../freetype/buildout.cfg
   ../libxml2/buildout.cfg
   ../pkgconfig/buildout.cfg
@@ -8,12 +7,14 @@ extends =
   ../zlib/buildout.cfg
   ../bzip2/buildout.cfg
   ../gperf/buildout.cfg
+  buildout.hash.cfg
 
 parts =
   fontconfig
 
 [fontconfig]
 recipe = slapos.recipe.cmmi
+shared = true
 url = http://fontconfig.org/release/fontconfig-2.12.6.tar.bz2
 md5sum = 733f5e2371ca77b69707bd7b30cc2163
 pkg_config_depends = ${freetype:pkg_config_depends}:${freetype:location}/lib/pkgconfig:${libxml2:location}/lib/pkgconfig
@@ -21,10 +22,15 @@ configure-options =
   --disable-static
   --disable-docs
   --enable-libxml2
-  --with-default-fonts=${fonts:location}
   --with-add-fonts=no
 environment =
   PATH=${pkgconfig:location}/bin:${gperf:location}/bin:%(PATH)s
   PKG_CONFIG_PATH=${:pkg_config_depends}
   CPPFLAGS=-I${zlib:location}/include -I${bzip2:location}/include
   LDFLAGS=-L${zlib:location}/lib -Wl,-rpath=${zlib:location}/lib -L${bzip2:location}/lib -Wl,-rpath=${bzip2:location}/lib
+
+[template-font-conf]
+recipe = slapos.recipe.template
+url = ${:_profile_base_location_}/${:filename}
+output = ${buildout:parts-directory}/${:_buildout_section_name_}
+mode = 640

component/fontconfig/buildout.hash.cfg

+[template-font-conf]
+filename = font.conf.in
+md5sum = 3600ce364c4fa240222fa12909b4109b
+

component/fontconfig/font.conf.in

+<?xml version="1.0"?>
+<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+{#
+ # Generates a font.conf to be used as FONTCONFIG_FILE environment variable.
+ #
+ # This template needs the following keys in context:
+ #
+ #  - cachedir: a directory to use a cachedir
+ #  - fonts: directories containing fonts ( \n separated list of paths )
+ #             for example {liberation-fonts:location}
+ #  - includes: directories fontconfig configuration ( \n separated list of paths )
+ #             typically, applications want to include {fontconfig:location}/etc/fonts/conf.d
+ #             also some fonts packages bundles font.d
+ #}
+<fontconfig>
+  <cachedir>{{ cachedir | escape}}</cachedir>
+  {% for font in fonts.splitlines() -%}
+    <dir>{{ font | escape}}</dir>
+  {% endfor %}
+  {% for include in includes.splitlines() -%}
+    <dir>{{ include | escape}}</dir>
+  {% endfor %}
+</fontconfig>
\ No newline at end of file

component/fonts/buildout.cfg

@@ -4,21 +4,24 @@ extends =
   ../p7zip/buildout.cfg
 
 parts =
-  liberation-fonts
-  ipaex-fonts
-  ipa-fonts
-  ocrb-fonts
   android-fonts
   dejavu-fonts
+  ipa-fonts
+  ipaex-fonts
+  liberation-fonts
+  ocrb-fonts
 
-[fonts]
-location = ${buildout:parts-directory}/${:_buildout_section_name_}
 
 [fonts-base]
-destination = ${fonts:location}/${:_buildout_section_name_}
-location = ${:destination}
-recipe = slapos.recipe.build:download-unpacked
-strip-top-level-dir = true
+# download and unpack, with shared parts support
+recipe = slapos.recipe.cmmi
+shared = true
+configure-command = :
+make-binary = :
+post-install = cp -ra . ${:location}
+location = @@LOCATION@@
+environment =
+  PATH=${xz-utils:location}/bin:%(PATH)s
 
 # Liberation(tm) Fonts - a font family which aims at metric
 # compatibility with Arial, Times New Roman, and Courier New.
@@ -61,7 +64,7 @@ md5sum = d0efec10b9f110a32e9b8f796e21782c
 # Microsoft's TrueType core fonts
 # non-free so not enabled by default
 [msttcore-fonts]
-location = ${fonts:location}/${:_buildout_section_name_}
+location = ${buildout:parts-directory}/${:_buildout_section_name_}
 recipe = slapos.recipe.build
 install =
   import os, subprocess