sv_clean_objs: prepend static svs to arena for sv_clean_objs

always call my_perl_destruct or fast_perl_destruct, which
prepends static svs to the sv_arenaroot, at global destruction.
not before as this would slow down del_sv.

move my_perl_destruct or fast_perl_destruct declaration to the front.
print the arena chains and sizes on -DD (static typically 3x smaller than the dynamic)