CMake Nightly Date Stamp
ExternalData: Test content link with a space in its name

Extend the Module.ExternalData test to cover a DATA{} reference whose
name contains a space.
Tests: Replace exec_program with execute_process

Drop use of the old exec_program command from CMake's own CMakeLists.txt
files.
Tests: Generalize decision for 'make' tool supporting spaces

Some make tools do not support spaces inside the source tree paths.
Decide early whether to add tests that depend on support for spaces so
we can use the result in a decision for any test.
Merge topic 'ExternalData-spaces' into next

d7f4468 Tests: Generalize decision for 'make' tool supporting spaces
3b3f132 Tests: Replace exec_program with execute_process
f0d1fe7 ExternalData: Test content link with a space in its name
3bb57ba CMake Nightly Date Stamp