Compare New York’s beleaguered City Hall with L.A.’s and be glad you live here. The last time I looked, Mad Rudy Giuliani’s charming Georgian headquarters was sealed off by cops and barricades. Protesters now get arrested and held overnight under the authority of Gotham’s power-maddened burgermeister, who — having begun his mayoral career with dramatic crime reductions — recently tried to slash library funding in the face of a budget surplus.Cut to 150 N. Los Angeles St. Where people throng our City Hall’s flower-bedecked lobby without even signing in. Outside which slogan-shouting pickets daily march with placards, unhindered. Where Mayor Dick Riordan himself awaits his elevator along with the rest of us. Makes you just love L.A., doesn’t it?But this pretty picture is darkened by one ugly fact: Riordan has his own Rudy Giuliani, just as inflexible and given to fits of pettiness. His name is Bernard Parks. He’s our chief of police.