When doing successive matches, track the input start and current search
start positions separately to prevent the `^` anchor from matching in
the middle of the string. Add policy CMP0186 to provide compatibility.
Issue: #26629Fixes: #16899
Every CPack generator sets default CPACK_PACKAGING_INSTALL_PREFIX
variable value differently so test framework should support
that correctly - previous version expected RPM/Deb /usr default and
removed it for Archive packagers as the default there is /.
Nikita Nemkin