[packagekit] [build] automatically disable components that are missing dependencies

[Frederic Peters]

Hello all,

In http://bugs.freedesktop.org/show_bug.cgi?id=25298 I asked if
PackageKit configure.ac could be changed to only enable Qt support when
the necessary libraries are found.

It is quite common for configure scripts to act that way, and packagers
who have to be sure to avoid building some components just have to pass
--disable-foobar.

The request targeted Qt as my primary concern is to have PackageKit in
JHBuild, because it has been accepted as an external dependency for
GNOME. Currently I have to force --disable-qt in the module definition,
while users would prefer if Qt was picked automatically if installed on
their systems.

But the same reasoning could as well be applied to other AC_ARG_ENABLE
commands (NetworkManager, ConnMan, browser plugin...).

In the bug report Richard wrote:

  I think the logic was to not have "silent" enabling and disabling of
  large chucks of PackageKit like this. If you email the mailing list we
  can discuss with the guys maintaining the build scripts what the logic
  was, and if it can be changed. Thanks.

So here I am.


Cheers,
        Frederic