Add platform configuration variable CMAKE_SYSTEM_IGNORE_PATH and user
configuration variable CMAKE_IGNORE_PATH. These specify a set of
directories that will be ignored by all the find commands. Update
FindPackageTest so that several cases will fail without a functioning
CMAKE_IGNORE_PATH.
The previous change to test finding in lib/cmake/<name>* weakened the
versioned find tests. Since the lib/cmake paths are searched before
lib/<name>* paths the previous change skipped requiring the command to
ignore zot-3.0 when finding zot-3.1. This change restores that and adds
zot-4.0 to test the lib/cmake path.
This teaches find_package to search
<prefix>/(share|lib)/cmake/<name>*/
for package configuration files. Packages that do not already have
files in a <prefix>/lib/<name>* directory can use this location to avoid
cluttering the lib directory.
Todd Gamblin
Brad King