The changes in commit 47b060ae (CPackDeb: allow empty directories in
component packages, 2015-09-21), commit b58de9fe (CPack: allow packaging
of empty directories, 2015-09-21), and commit b761e90d (CPack: remove
accidental changes, 2015-09-22) regressed packaging of CMake itself.
Revert the changes until they can be revised and rebased on other
changes that make additional fixes.
Move PARTIALLY_RELOCATABLE_WARNING test to the new common CPack test
script structure to have all tests in one place as well as additional
benefit of having some more checks done during test execution.