Only use <=1/2 available user processes during fork_stress test.
Allow tests that show CPUID divergences to opt-in to CPU binding.
Log catastrophic bind() failures.
Revert "Log catastrophic bind() failures."

This reverts commit 1161e5cfd0b1196d08262ff40f2786a2e7e157fa.
Handle EINVAL errors from bind().
checkpoint
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cleanup
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trivial