Don't generate self-references for system include directories.

Targets which link directly to themselves should not result in
generate-time errors (reported by the DAG checker).

Self-links are handled separately with policy CMP0038.
Help: Fix up the VISIBILITY_INLINES_HIDDEN docs.

Resolve some sentence fragments, remove a copy-pasto from other docs
and use a link to the CMAKE_VISIBILITY_INLINES_HIDDEN variable.
Make the cmStrictTargetComparison operate on const cmTarget*.
Merge topic 'minor-cleanups'

259bf09 Make the cmStrictTargetComparison operate on const cmTarget*.
8cc3cdb Help: Fix up the VISIBILITY_INLINES_HIDDEN docs.
1396ab8 Don't generate self-references for system include directories.
Tests/Contracts: Update test for VTK release branch

The plan is to reinstate the VTK contracts test so that CMake
& VTK devs will both be made aware when a change in CMake causes
build problems for VTK.
Merge topic 'vtk-contract'

1b173f2 Tests/Contracts: Update test for VTK release branch