Currently using go-fuzz with code using golang.org/x/crypto/ssh fails
because it passes CertTimeInfinity to an interface{} and automatically
tries to use an int, which overflows and results in a compile error.
This change adds a no-op type conversion inside the function which
makes things compile with go-fuzz.
Change-Id: Iade0c0df7e20cbac4928480fad3e44c831e1e00a
Reviewed-on: https://go-review.googlesource.com/11285
Reviewed-by: Adam Langley <agl@golang.org>