include
-------

Load and run CMake code from a file or module.

::

  include(<file|module> [OPTIONAL] [RESULT_VARIABLE <VAR>]
                        [NO_POLICY_SCOPE])

Load and run CMake code from the file given.  Variable reads and
writes access the scope of the caller (dynamic scoping).  If OPTIONAL
is present, then no error is raised if the file does not exist.  If
RESULT_VARIABLE is given the variable will be set to the full filename
which has been included or NOTFOUND if it failed.

If a module is specified instead of a file, the file with name
<modulename>.cmake is searched first in CMAKE_MODULE_PATH, then in the
CMake module directory.  There is one exception to this: if the file
which calls include() is located itself in the CMake module directory,
then first the CMake module directory is searched and
CMAKE_MODULE_PATH afterwards.  See also policy CMP0017.

See the cmake_policy() command documentation for discussion of the
NO_POLICY_SCOPE option.