cmTarget: Deprecate COMPILE_DEFINITIONS_ properties with a policy.
Genex: Use case-sensitive comparison for COMPILER_ID.
FindQt4: Fix use of get_target_property to use actual target name.

This was introduced in ba48e63f (Generate config-specific interface
link libraries propeties., 2013-02-09).
FindQt4: Ensure target exists before calling get_target_property.

This macro is called for all potential Qt targets, even those which were
not found.
get_target_property: Error on non-existent target.

Introduce policy CMP0045 to control this behavior.
Merge topic 'policies' into next

73e9340 get_target_property: Error on non-existent target.
ab9f58f FindQt4: Ensure target exists before calling get_target_property.
37ebeb9 FindQt4: Fix use of get_target_property to use actual target name.
6aabb6a Genex: Use case-sensitive comparison for COMPILER_ID.
5bb53f6 cmTarget: Deprecate COMPILE_DEFINITIONS_ properties with a policy.