Update hicolor-icon-theme required version in external dependencies

[Luca Ferretti <elle uca libero it>]

The currently required version is 0.9 [1] but recently was released the
0.10, supporting the installation of named icons in new contexts defined
in Icon Naming Spec [2]

What's the difference? It's simple, let me assume that you want to
provide named icons for your application using the trick explained by
Rodney in his blog[3] under the "Status" context.

If your system is using the version 0.9 of hicolor, you can install your
icons in $prefix/share/<appname>/icons/hicolor/<size>/status, but those
icons will be ignored at runtime, 'cause the list of directories to
watch in system or local `hicolor` directories is defined in the
index.theme provided by hicolor-icon-theme. 

The new 0.10 release of hicolor-icon-theme adds those missing
directories.

If it's OK, I'll provide to update the page on wiki and the jhbuild
module.

PS by now there is no way to check the installed version of hicolor icon
theme. Alex asked me to co-maintain this module, so maybe in the next
future will be a 0.12 release providing pkgconfig support as in
gnome-icon-theme


[1] http://live.gnome.org/TwoPointSeventeen/ExternalDependencies
[2] http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html
[3] http://wayofthemonkey.com/index.php?date=2006-11-15&month=11&year=2006