target_link_libraries: Optionally require only target names
Optionally verify that items in LINK_LIBRARIES
and
INTERFACE_LINK_LIBRARIES
that can be target names are actually target
names. Add a LINK_LIBRARIES_ONLY_TARGETS
target property and
corresponding CMAKE_LINK_LIBRARIES_ONLY_TARGETS
variable to enable
this new check.
Fixes: #22858 (closed)