Issue a deprecation warning on calls to `cmake_minimum_required` or
`cmake_policy` that set policies based on versions older than 3.5.
Note that the effective policy version includes `...<max>` treatment.
Update the check from commit 5845c218d7 (Deprecate compatibility with
CMake versions older than 2.8.12, 2020-06-12, v3.19.0-rc1~629^2).
For policy-specific tests, use the version before the policy was
introduced. Otherwise, use 3.5 where possible.
Also, remove `cmake_minimum_required()` and `project()` calls from
individual cases where they are handled by `CMakeLists.txt`.
The OLD behaviors of all policies are deprecated, but only by
documentation. Add an explicit deprecation diagnostic for some policies
to encourage projects to port away from setting policies to OLD.
Fix test cases whose behavior differs when their source or build tree is
under CMAKE_INSTALL_PREFIX by setting an install prefix under the build
tree. Otherwise they may fail when run under the default install prefix
(e.g. /usr/local).
The moved tests are related to paths in INTERFACE_INCLUDE_DIRECTORIES
in general, and when exporting, and covering cases of the install
location being within the build or source prefix etc. Other build
properties containing paths should have similar tests, so this
allows some parameterization while keeping the preparation of the
various directory structures.
