nproc: process space in OMP_NUM_THREADS

[cuiweixie]

in GNU nproc:

OMP_NUM_THREADS="4 ,8" nproc

output:

4

[cakebaker]

Can you please add a test to test_nproc.rs to ensure we don't regress in the future? Thanks.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/seq/seq-epipe. tests/seq/seq-epipe is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/follow-name (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/tail/tail-n0f is no longer failing!
Congrats! The gnu test tests/basenc/bounded-memory is now passing!
Congrats! The gnu test tests/rm/many-dir-entries-vs-OOM is now passing!

[cuiweixie]

Can you please add a test to test_nproc.rs to ensure we don't regress in the future? Thanks.

Done

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/misc/io-errors. tests/misc/io-errors is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/tail/tail-n0f is no longer failing!
Congrats! The gnu test tests/basenc/bounded-memory is now passing!
Congrats! The gnu test tests/rm/many-dir-entries-vs-OOM is now passing!

[cakebaker]

Thanks for your PR!