nproc: OMP_NUM_THREADS=NaN should reject quota if fifo schedular is used

[oech3]

$ run0 systemd-run --scope -q -p CPUQuota=100% chrt --fifo 10 env OMP_NUM_THREADS=NaN nproc
1
$ run0 systemd-run --scope -q -p CPUQuota=100% chrt --fifo 10 env OMP_NUM_THREADS=NaN '/home/a/bin/gnu9.11/nproc'
12