make various compiler instrumentation flags "advanced" options

# GNU compiler features

if (${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU")

  option(ENABLE_COVERAGE "Enable code coverage" OFF)

  mark_as_advanced(ENABLE_COVERAGE)

  if(ENABLE_COVERAGE)

    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --coverage")

  endif()

  option(ENABLE_SANITIZE_ADDRESS "Enable address sanitizer" OFF)

  mark_as_advanced(ENABLE_SANITIZE_ADDRESS)

  if(ENABLE_SANITIZE_ADDRESS)

    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")

  endif()

  option(ENABLE_SANITIZE_UNDEFINED "Enable undefined behavior sanitizer" OFF)

  mark_as_advanced(ENABLE_SANITIZE_UNDEFINED)

  if(ENABLE_SANITIZE_UNDEFINED)

    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=undefined")

  endif()

  option(ENABLE_SANITIZE_THREAD "Enable thread sanitizer" OFF)

  mark_as_advanced(ENABLE_SANITIZE_THREAD)

  if(ENABLE_SANITIZE_THREAD)

    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=thread")

  endif()