Use one authorative source of the LINK_LIBRARIES property.

We populate and maintain a vector of structs to keep track of
backtraces already, so no need to populate the Properties container
additionally.

For completeness, it is necessary to remove the condition for
populating the vector for only valid library names and generator
expressions. That condition is now determined when evaluating the
generator expressions.
Merge topic 'authorative-LINK_LIBRARIES' into next

f01dc72 Use one authorative source of the LINK_LIBRARIES property.