Ensure cxxtest output directories are created

Ninja & Visual Studio cope with creating the directories themselves,
however Make does not create them.
Refs #0

buildconfig/CMake/FindCxxTest.cmake

@@ -107,6 +107,9 @@ macro(CXXTEST_ADD_TEST _cxxtest_testname)
     set (_cxxtest_output_dir ${CMAKE_CURRENT_BINARY_DIR})
     if (CXXTEST_OUTPUT_DIR)
       set (_cxxtest_output_dir ${CXXTEST_OUTPUT_DIR})
+      if ( NOT IS_DIRECTORY "${_cxxtest_output_dir}")
+        file ( MAKE_DIRECTORY "${_cxxtest_output_dir}" )
+      endif()
     endif()
     # determine the cpp filename
     set(_cxxtest_real_outfname ${_cxxtest_output_dir}/${_cxxtest_testname}_runner.cpp)