Move gc to package org.eclipse.jgit.pgm

All bugs reported for gc have been fixed and it seems we reached a
stable implementation.

Change-Id: I78a96ee2103beb48325da0f6ee10b2498bdc0267
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.pgm/META-INF/services/org.eclipse.jgit.pgm.TextBuiltin

 org.eclipse.jgit.pgm.Diff
 org.eclipse.jgit.pgm.DiffTree
 org.eclipse.jgit.pgm.Fetch
+org.eclipse.jgit.pgm.Gc
 org.eclipse.jgit.pgm.Glog
 org.eclipse.jgit.pgm.IndexPack
 org.eclipse.jgit.pgm.Init
 org.eclipse.jgit.pgm.Version
 
 org.eclipse.jgit.pgm.debug.DiffAlgorithms
-org.eclipse.jgit.pgm.debug.Gc
 org.eclipse.jgit.pgm.debug.MakeCacheTree
 org.eclipse.jgit.pgm.debug.ReadDirCache
 org.eclipse.jgit.pgm.debug.RebuildCommitGraph

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/debug/Gc.java → org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Gc.java

  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package org.eclipse.jgit.pgm.debug;
+package org.eclipse.jgit.pgm;
 
 import org.eclipse.jgit.internal.storage.file.FileRepository;
 import org.eclipse.jgit.internal.storage.file.GC;
 import org.eclipse.jgit.lib.TextProgressMonitor;
-import org.eclipse.jgit.pgm.TextBuiltin;
 
 class Gc extends TextBuiltin {
 	@Override