cmake DIMMER_HAS_LIBGC examples

AXErunners/axe src/immer/CMakeLists.txt :116 

target_compile_definitions(immer-dev INTERFACE
  -DIMMER_CXX_STANDARD=${CXX_STANDARD}
  -DIMMER_HAS_LIBGC=1
  -DIMMER_NO_FREE_LIST=${DISABLE_FREE_LIST}
  -DIMMER_NO_THREAD_SAFETY=${DISABLE_THREAD_SAFETY}
  -DIMMER_SLOW_TESTS=${CHECK_SLOW_TESTS}
  -DFMT_HEADER_ONLY=1)

arximboldi/immer CMakeLists.txt :145 

target_compile_definitions(
  immer-dev
  INTERFACE -DIMMER_CXX_STANDARD=${CXX_STANDARD}
            -DIMMER_HAS_LIBGC=1
            -DIMMER_NO_FREE_LIST=${DISABLE_FREE_LIST}
            -DIMMER_NO_THREAD_SAFETY=${DISABLE_THREAD_SAFETY}
            -DIMMER_SLOW_TESTS=${CHECK_SLOW_TESTS}
            -DFMT_HEADER_ONLY=1)