Fix tests for MacOS and Windows

Fix tests for MacOS and Windows

* maintMakefile: Remove the template headers as prerequisites.
* tests/scripts/features/jobserver: Only test fifo if enabled.
* tests/scripts/variables/INCLUDE_DIRS: On MacOS none of the default
directories exist so .INCLUDE_DIRS is empty by default.
* tests/scripts/features/se_explicit: Fail via exit.  cp will show
different error messages on different systems.
* tests/scripts/features/se_implicit: Ditto.
* tests/scripts/features/se_statpat: Ditto.