message: fixes MPI tests
diff: set(gko_test_single_args "MPI_SIZE")
  -set(gko_test_multi_arg "DISABLE_EXECUTORS;ADDITIONAL_LIBRARIES;ADDITIONAL_INCLUDES")
  +set(gko_test_multi_args "DISABLE_EXECUTORS;ADDITIONAL_LIBRARIES;ADDITIONAL_INCLUDES")
  ## Replaces / by _ to create valid target names from relative paths
  function(ginkgo_build_test_name test_name target_name)
  @@ -21,7 +21,7 @@ endfunction(ginkgo_create_gtest_mpi_main)
  ## Set up shared target properties and handle ADDITIONAL_LIBRARIES/ADDITIONAL_INCLUDES
  ## `MPI_SIZE size` causes the tests to be run with `size` MPI processes.
  function(ginkgo_set_test_target_properties test_target_name)
  - cmake_parse_arguments(PARSE_ARGV 1 set_properties "" "${gko_test_single_args}" "${gko_test_multi_arg}")
  + cmake_parse_arguments(PARSE_ARGV 1 set_properties "" "${gko_test_single_args}" "${gko_test_multi_args}")
  if (GINKGO_FAST_TESTS)
  target_compile_definitions(${test_target_name} PRIVATE GINKGO_FAST_TESTS)
  endif()
  @@ -52,7 +52,7 @@ endfunction()
  ## - `ADDITIONAL_LIBRARIES lib1 lib2` adds additional target link dependencies
  ## - `ADDITIONAL_INCLUDES path1 path2` adds additional target include paths
  function(ginkgo_add_test test_name test_target_name)
  - cmake_parse_arguments(PARSE_ARGV 2 add_test "" "${gko_test_single_arg}" "${gko_test_multi_arg}")
  + cmake_parse_arguments(PARSE_ARGV 2 add_test "" "${gko_test_single_args}" "${gko_test_multi_args}")
  file(RELATIVE_PATH REL_BINARY_DIR ${PROJECT_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR})
  set_target_properties(${test_target_name} PROPERTIES OUTPUT_NAME ${test_name})
  if (add_test_MPI_SIZE)
  @@ -201,7 +201,7 @@ function(ginkgo_create_common_test test_name)
  endfunction(ginkgo_create_common_test)
  function(ginkgo_create_common_test_internal test_name exec_type exec)
  - cmake_parse_arguments(PARSE_ARGV 3 common_test "" "${gko_test_single_arg}" "${gko_test_multi_arg}")
  + cmake_parse_arguments(PARSE_ARGV 3 common_test "" "${gko_test_single_args}" "${gko_test_multi_args}")
  if(exec IN_LIST common_test_DISABLE_EXECUTORS)
  return()
  endif()
  @@ -223,7 +223,7 @@ endfunction(ginkgo_create_common_test_internal)
  ## Common test compiled with the device compiler, one target for each enabled backend
  function(ginkgo_create_common_device_test test_name)
  - cmake_parse_arguments(PARSE_ARGV 1 common_device_test "" "${gko_test_single_arg}" "${gko_test_multi_arg}")
  + cmake_parse_arguments(PARSE_ARGV 1 common_device_test "" "${gko_test_single_args}" "${gko_test_multi_args}")
  ginkgo_build_test_name(${test_name} test_target_name)
  if(GINKGO_BUILD_DPCPP)
  ginkgo_create_common_test_internal(${test_name} DpcppExecutor dpcpp ${ARGN})
  