They are currently not given a size, which makes the DWARF reader
very confused. Particularly things like [4]func() get a size of -4, not 32.

Fixes #21097

Change-Id: I01e754134d82fbbe6567e3c7847a4843792a3776
Reviewed-on: https://go-review.googlesource.com/55551Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>