CVS clients recognize file modifications only if a file's timestamp is
newer than its CVS/Entries line. This fixes intermittent failure of the
test on filesystems with low timestamp resolution by delaying before
creating a local modification.
This creates new tests "CTest.UpdateSVN" and "CTest.UpdateCVS". They
test that the Update.xml produced by CTest for a version-controlled
project contains entries for files added, changed, and removed.