Teach add_custom_target to check the policy too. Extend the policy to
disallow reserved target names that we use for builtin targets like
"all".
Extend the RunCMake.CMP0037 test to cover these cases.
Split the test cases covering spaces and colons into separate units.
Run the space cases everywhere. Disable the colon cases where they
are known to fail. This approach increases platform coverage for the
test and makes the known-failure logic as local as possible.
No Makefile generator on Windows can generate targets with ':'
in their name because the CMakeFiles/<target>.dir directory cannot
be created. Skip this part of the test on all Windows Make tools.
Brad King
Nils Gladitz
Stephen Kelly