message: Fix build when OpenMP is not found.
diff: @@ -31,7 +31,7 @@ if(BUILD_OMP)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
  set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
  else(OPENMP_FOUND)
  - set(BUILD_OMP OFF CACHE FORCE)
  + set(BUILD_OMP OFF CACHE BOOL "" FORCE)
  endif(OPENMP_FOUND)
  endif(BUILD_OMP)
  