Convert all xbps-base-chroot pkgs to subpkgs.

Also introduce "libs.depends", that adds a rundep of a package
with a proper version. This is to avoid modifying all dependent
packages if there's an API/ABI change.

--HG--
extra : convert_revision : a46b11b8e9187bdb2bfc954ad5ff40ecd9c0fe31

templates/zlib/template

@@ -1,5 +1,6 @@
 # Template build file for 'zlib'
 pkgname=zlib
+sourcepkg=zlib
 version=1.2.3
 distfiles="http://www.zlib.net/$pkgname-$version.tar.bz2"
 build_style=configure
@@ -14,4 +15,4 @@ long_desc="
  by RFCs (Request for Comments) 1950 to 1952."
 
 base_chroot=yes
-run_depends="glibc-2.8"
+subpackages="dev libs"