Fix style.
Ensure clean INTERFACE_INCLUDE_DIRECTORIES on install(EXPORT)

Check that source and binary directories are not part of the
INTERFACE_INCLUDE_DIRECTORIES for installed IMPORTED targets.

This is limited to directories which do not contain generator
expressions to evaluate. Such paths can only be checked at time
of use of the imported target, which will be done in a follow up
patch.
Make targets report an error on faulty INTERFACE on IMPORTED targets.

It is considered an error if the INTERFACE_INCLUDE_DIRECTORIES contains
a directory which does not exist, which indicates a programmer error
by the upstream, or a packaging error.
Merge topic 'error-on-exported-missing-include-dir' into next

1d7a181 Fix style.
Merge topic 'error-on-exported-missing-include-dir' into next

6253d6f Make targets report an error on faulty INTERFACE on IMPORTED targets.
8062909 Ensure clean INTERFACE_INCLUDE_DIRECTORIES on install(EXPORT)
Incremenat the number of trys for git clones.

This fixes a bug where the number of try variable was not
incremented each time a git clone was attempted.
Merge topic 'ep_retry_clone' into next

909b9f7 Incremenat the number of trys for git clones.
Remove content from INTERFACE_INCLUDE_DIRECTORIES in test.

The content is not needed, and now causes additional errors.
Merge topic 'error-on-exported-missing-include-dir' into next

061acbb Remove content from INTERFACE_INCLUDE_DIRECTORIES in test.