[PATCH] cvs2git.c: support incremental conversion

[PATCH] cvs2git.c: support incremental conversion

Add -u option to indicate incremental conversion.

I wanted to be able to track CVS repositories in a GIT repository.  The
cvs2git program worked fine with the initial import but needed a tiny
modification to enable me to resync the GIT repository with the updated
CVS tree.

[ The original version of this patch failed to track the correct
  branch on the first new commit. Fixed and tested by Sven. ]

Signed-off-by: Panagiotis Issaris <takis@lumumba.luc.ac.be>
Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>