find_dependency: Unset temporary variables before returning

Modules/CMakeFindDependencyMacro.cmake

@@ -53,11 +53,12 @@ macro(find_dependency dep)
     set_property(GLOBAL PROPERTY _CMAKE_${dep}_TRANSITIVE_DEPENDENCY TRUE)
   endif()
 
+  unset(cmake_fd_alreadyTransitive)
+  unset(cmake_fd_quiet_arg)
+  unset(cmake_fd_required_arg)
   if (NOT ${dep}_FOUND)
     set(${CMAKE_FIND_PACKAGE_NAME}_NOT_FOUND_MESSAGE "${CMAKE_FIND_PACKAGE_NAME} could not be found because dependency ${dep} could not be found.")
     set(${CMAKE_FIND_PACKAGE_NAME}_FOUND False)
     return()
   endif()
-  set(cmake_fd_required_arg)
-  set(cmake_fd_quiet_arg)
 endmacro()