eal: restrict control threads to startup CPU affinity

eal: restrict control threads to startup CPU affinity

Spawning the ctrl threads on anything that is not part of the eal
coremask is not that polite to the rest of the system, especially
when you took good care to pin your processes on cpu resources with
tools like taskset (linux) / cpuset (freebsd).

Rather than introduce yet another eal options to control on which cpu
those ctrl threads are created, let's take the startup cpu affinity
as a reference and remove the eal coremask from it.
If no cpu is left, then we default to the master core.

The cpuset is computed once at init before the original cpu affinity
is lost.

Introduced a RTE_CPU_AND macro to abstract the differences between linux
and freebsd respective macros.

Examples in a 4 cores FreeBSD vm:

$ ./build/app/testpmd -l 2,3 --no-huge --no-pci -m 512 \
 -- -i --total-num-mbufs=2048

$ procstat -S 1057
  PID    TID COMM                TDNAME              CPU CSID CPU MASK
 1057 100131 testpmd             -                     2    1 2
 1057 100140 testpmd             eal-intr-thread       1    1 0-1
 1057 100141 testpmd             rte_mp_handle         1    1 0-1
 1057 100142 testpmd             lcore-slave-3         3    1 3

$ cpuset -l 1,2,3 ./build/app/testpmd -l 2,3 --no-huge --no-pci -m 512 \
 -- -i --total-num-mbufs=2048

$ procstat -S 1061
  PID    TID COMM                TDNAME              CPU CSID CPU MASK
 1061 100131 testpmd             -                     2    2 2
 1061 100144 testpmd             eal-intr-thread       1    2 1
 1061 100145 testpmd             rte_mp_handle         1    2 1
 1061 100147 testpmd             lcore-slave-3         3    2 3

$ cpuset -l 2,3 ./build/app/testpmd -l 2,3 --no-huge --no-pci -m 512 \
 -- -i --total-num-mbufs=2048

$ procstat -S 1065
  PID    TID COMM                TDNAME              CPU CSID CPU MASK
 1065 100131 testpmd             -                     2    2 2
 1065 100148 testpmd             eal-intr-thread       2    2 2
 1065 100149 testpmd             rte_mp_handle         2    2 2
 1065 100150 testpmd             lcore-slave-3         3    2 3

Fixes: d651ee4919cd ("eal: set affinity for control threads")
Cc: stable@dpdk.org
Signed-off-by: David Marchand <david.marchand@redhat.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
Reviewed-by: Olivier Matz <olivier.matz@6wind.com>