* rename genl to nl:
"genl" is not very specific without more context. and libnl is actually
a library suite. so it would be better if we can rename the library to
be found to "libnl", and by following the naming convention of CMake,
in this change, Findgenl.cmake is renamed to Findnl.cmake
* Findnl.cmake: support the component argument, in our specific case,
what we want is "libnl-genl" library, which is one of the libraries
offered by libnl. so let's just make it a component.
* Findnl.cmake: should pass the names of the required variables instead of
their values to `find_package_handle_standard_args()`. before this
change, we pass `GENL_LIBRARIES` to this function. it was correct at the
first glance. but it is not able to handle the case where case where
libnl-genl is not installed. so the fix is to pass all the names of
required library paths to this function. in this change, their name
are concatenated to a single variable -- `nl_LIBRARIES`, and the
value of this variable is passed to
`find_package_handle_standard_args()`. and the error message would
be more specific this way if libnl-genl is not found:
Could NOT find nl (missing: nl_genl_LIBRARY)
* Findnl.cmake: add nl::<component> as imported library, it helps the
consumer of these libraries to import them -- no need to
specify the `target_include_directories()` separately anymore.
* move the find_package() code to where it is used. it helps to improve
the readability.
* remove `HAVE_GENL` variable: it's not used anywhere.
* drop the messages of "Not using foobar", they do not help.
Signed-off-by: Kefu Chai <kchai@redhat.com>
