CTest.UpdateP4: Fix test when p4 client is not in PATH
CTest.UpdateP4: Run test in directory with space in its name

All the other VCS tool tests use "CTest Update$VCS", so do the same
for P4.
Merge topic 'ctest-p4' into next

9a75213 CTest.UpdateP4: Run test in directory with space in its name
ee51ec64eb CTest.UpdateP4: Fix test when p4 client is not in PATH