cmake: Set CMP0074 to NEW

cmake: Set CMP0074 to NEW

This is to address the following configuration warning reported
when configuring LibArchive passing ZLIB_ROOT option:

  CMake Warning (dev) at CMakeLists.txt:393 (FIND_PACKAGE):
    Policy CMP0074 is not set: find_package uses <PackageName>_ROOT variables.
    Run "cmake --help-policy CMP0074" for policy details.  Use the cmake_policy
    command to set the policy and suppress this warning.

    CMake variable ZLIB_ROOT is set to:

      /path/to/zlib-install

    For compatibility, CMake is ignoring the variable.
  This warning is for project developers.  Use -Wno-dev to suppress it.

Co-authored-by: Matt McCormick <matt.mccormick@kitware.com>