message: Added missing CheckCXXSourceCompiles include.
diff: @@ -177,6 +177,7 @@ else()
  endif()
  set(CPP_ATOMIC_LIBRARY "")
  +include(CheckCXXSourceCompiles)
  if(NOT MSVC)
  # Some platforms require a explicit linkage against libatomic to operate on 64-bit numbers
  set(TEST_SOURCE "
  