[bugfix,dunecontrol] Fixes check whether to path --with-<dune-module> to configure

The check was whether $module_inst is yes, but what we actually want to check
is $INT_$module. This patch fixes this and forces configure to use pkg-config
for the installed module again. Only this allows us to extract custom libdirs.
(cherry picked from commit 0c2857db3193d20c5aaa2578d00a9d68bb97d9d7)

Signed-off-by: Markus Blatt <markus@dr-blatt.de>