'-n' option.
Look for updates in the default locations only after user-supplied
locations are tried.
If newer microcode files are put into non-standard path, both measures
allow to avoid situation where older update loaded from the default
path first, and then the second update is applied from non-standard
path. Applying intermediate updates might be undesirable.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
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