Allow find_package to prefer Config mode. See issue #16805
Points of interest:
- The existing variable
CMAKE_FIND_PACKAGE_WARN_NO_MODULE
is ignored whenCMAKE_FIND_PACKAGE_PREFER_CONFIG
isTRUE
because one variable states you want to enforce an explicit mode and the other states you want to use an implicit mode. - The note about
<pkg>Config.cmake
result variables is included in the variable's help page. - I did not rebuild the help files when testing so please review the doc changes carefully.