Tests: Simplify ExternalProjectUpdate test arguments

Drop the -DCMAKE_TEST_MAKEPROGRAM argument because the value is not
used inside the test script.

Tests/CMakeLists.txt

@@ -1141,7 +1141,6 @@ ${CMake_BINARY_DIR}/bin/cmake -DVERSION=master -P ${CMake_SOURCE_DIR}/Utilities/
     -DExternalProjectUpdate_BINARY_DIR:PATH=${CMake_BINARY_DIR}/Tests/ExternalProjectUpdate
     -DCMAKE_TEST_GENERATOR=${CMAKE_TEST_GENERATOR}
     -DCMAKE_TEST_GENERATOR_TOOLSET=${CMAKE_TEST_GENERATOR_TOOLSET}
-    -DCMAKE_TEST_MAKEPROGRAM=${CMAKE_TEST_MAKEPROGRAM}
     -DCMAKE_CTEST_COMMAND=${CMAKE_CTEST_COMMAND}
     -P ${CMake_SOURCE_DIR}/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
     )