When running CMake from the build tree the CMAKE_ROOT is the
entire source tree. Fix the CMP0017 check to be specific to
the Modules/ directory under CMAKE_ROOT so that Tests/ does
not count. Fix the FindPackageTest modules to include FPHSA
by full path from CMAKE_ROOT so that they do not include the
local FPHSA which reports an error meant to test that CMP0017
works.
In the new mode FPHSA now accepts a FOUND_VAR option, which can be set
either to ExactCase_FOUND or UPPERCASE_FOUND, no other values are
accepted. Also add tests for that, including failure.
Alex