package: use ONLY ONE shallow Git clone in Jenkins CI.

Not sepearate clone and workspace for each configuration combination.
Why the hell is that default.
package: Jenkins cleanup.

 * More descriptive configuration names. That damn thing shows only the
   values and not the variables, thus having ON and OFF repeated five
   times doesn't help much.
 * Use -fPIC for building static libraries.
 * Install to filesystem/ subdirectory so we don't mess up the
   JENKINS_HOME.
package: work around Jenkins inability to use anything else than JUnit.

Why do I need a plugin to manually set "Test Failed" state?!
package: don't schedule building of depending projects in Jenkins.

Magnum has 64 targets and in many cases the rebuild is not needed.
package: retry with git pull if it fails.

Jenkins has absolutely useless support for sharing one git directory by
multiple configurations. It tries to do the pull from all the workers at
one time.
Utility: don't forget to enable -fPIC also for CorradeUtilityObjects.