arm64/amd64: add options IOMMU to LINT

[kib]

Why did you removed IOMMU from i386 LINT?
Also, I do not think that adding IOMMU to LINT on amd64/arm64 is right.

The idea of LINT is to be complimentary to GENERIC, so that make universe checks as much code as possible. Adding the IOMMU option to both LINT and GENERIC makes the configuration without IOMMU not compile-time checked. [This is why IOMMU is in i386 LINT but not GENERIC]

[mhorne]

In D35579#807168, @kib wrote:

Why did you removed IOMMU from i386 LINT?
Also, I do not think that adding IOMMU to LINT on amd64/arm64 is right.

The idea of LINT is to be complimentary to GENERIC, so that make universe checks as much code as possible. Adding the IOMMU option to both LINT and GENERIC makes the configuration without IOMMU not compile-time checked. [This is why IOMMU is in i386 LINT but not GENERIC]

It is somewhat confusing because NOTES acts both as a source for LINT and as documentation of all existing config options. So it is easy to think "the LINT config builds everything".

But you are right, as usual, that having this option excluded from LINT is much more useful, and more in line with its actual purpose.