Use CMakePackageConfigHelpers for package config file

This makes the CMake package relocatable

packaging/CMakeLists.txt

@@ -49,10 +49,10 @@ write_basic_package_version_file(
 
 file(READ "../cmake/HandlePolicies.cmake" HANDLE_POLICIES_SCRIPT OFFSET 1128)
 
-configure_file(
+configure_package_config_file(
     "LoadStaticSharedTargetsConfig.cmake.in"
     "${CMAKE_CURRENT_BINARY_DIR}/LoadStaticSharedTargetsConfig.cmake"
-    @ONLY
+    INSTALL_DESTINATION "${LoadStaticSharedTargets_INSTALL_CMAKEDIR}"
 )
 
 install(

packaging/LoadStaticSharedTargetsConfig.cmake.in

@@ -23,6 +23,8 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 ]]
 
+@PACKAGE_INIT@
+
 cmake_minimum_required(VERSION @CMAKE_MINIMUM_REQUIRED_VERSION@)
 
 set(CMAKE_MAXIMUM_SUPPORTED_VERSION @CMAKE_MAXIMUM_SUPPORTED_VERSION@)
@@ -33,3 +35,5 @@ set(CMAKE_MAXIMUM_SUPPORTED_VERSION @CMAKE_MAXIMUM_SUPPORTED_VERSION@)
 
 # include(LoadStaticSharedTargets) should work after this
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
+
+check_required_components(LoadStaticSharedTargets)