ssh/terminal: add support for tamago

[abarisani]

This commit broke use of ssh/terminal within GOOS=tamago.

In a manner similar to what has been done for zos this would fix that.

Thank you

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[abarisani]

@googlebot I signed it!

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[empijei]

cc @FiloSottile

[gopherbot]

Message from Andrea Barisani:

Patch Set 1:

(1 comment)

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[gopherbot]

Message from Andrea Barisani:

Patch Set 1:

(1 comment)

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