sched, isolcpu: make cpu_isolated_map visible outside scheduler

sched, isolcpu: make cpu_isolated_map visible outside scheduler

Needed by the next patch. Also makes cpu_isolated_map present
when compiled without SMP and/or with CONFIG_NR_CPUS=1, like
the other cpu masks.

At some point we may want to clean things up so cpumasks do
not exist in UP kernels. Maybe something for the CONFIG_TINY
crowd.

Cc: Peter Zijlstra <[email protected]>
Cc: Clark Williams <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Luiz Capitulino <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: [email protected]
Signed-off-by: Rik van Riel <[email protected]>
Acked-by: Zefan Li <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>