cmd/compile: allow inlining simple functions that use for.

[OneOfOne]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

Go 1.8, 1.9rc2, master.

What operating system and processor architecture are you using (go env)?

amd64

What did you do?

https://play.golang.org/p/jGYlhKirNX

go build -gcflags "-m -m"

What did you expect to see?

./blah.go:8:6: can inline Fnv32

What did you see instead?

./blah.go:8:6: cannot inline Fnv32: unhandled op for
./blah.go:18:6: can inline Fnv32Inline ..........

I feel like this a dup and I apologize if it is, my searching skills have failed me.

@josharian @dr2chase @randall77

[ALTree]

That would be #14768.

[mvdan]

Dup indeed.