Merge topic 'genex-LINK_LIBRARY-to-decorate-library'

2a6b0415d7 $<LINK_LIBRARY>: Add LINK_LIBRARY_OVERRIDE target property
42965799b4 Genex: Add $<LINK_LIBRARY:...>
78dd7d5292 cmRulePlaceholderExpander: add base class for placeholder expansion reuse
4b55828a9f cmExpandListWithBacktrace: add handling of empty elements.
28d7432468 cmComputeLinkInformation: use cmComputeLinkDepends::LinkEntry

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6769