Because cmake_parse_arguments() has been implemented as a native
command, there is no need to include(CMakeParseArguments) anymore.
Its inclusion has been removed from several CMake modules.
Tests/CMakeOnly/CMakeLists.txt has been changed to include the
*building* CMake's copy of CMakeParseArguments rather than the
*built* CMake's copy. This file included the *built* copy because
when this file was introduced, CMake could still be built with versions
that didn't supply cmake_parse_arguments(). Now, CMake requires 3.1 or
greater, where cmake_parse_arguments() existed but was still in the
form of a module, so we include it from the *building* CMake.
88b40744b5