remove useless bsd/memory_openbsd.cc
remove useless bsd/memory_openbsd.cc

thewtex/tmux-mem-cpu-load,thewtex/tmux-mem-cpu-load,allcatsarebeautiful/tmux-mem-cpu-load,allcatsarebeautiful/tmux-mem-cpu-load,allcatsarebeautiful/tmux-mem-cpu-load,allcatsarebeautiful/tmux-mem-cpu-load,thewtex/tmux-mem-cpu-load,thewtex/tmux-mem-cpu-load