syscall: hide internal comment from Syscall documentation
syscall: hide internal comment from Syscall documentation

There's a comment on the Syscall function that's supposed to be an
internal implementation note, but since it's not separated from the
function definition, it appears in godoc. Add a blank line to prevent
this.

Change-Id: Iba307f1cc3844689ec3c6d82c21d441852e35bca
Reviewed-on: https://go-review.googlesource.com/c/go/+/236561
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

nawawi/go,akutz/go,golang/go,akutz/go,golang/go,nawawi/go,golang/go,nawawi/go,cloudflare/go,cloudflare/go,golang/go,akutz/go,akutz/go,CAFxX/go,golang/go,akutz/go,CAFxX/go,cloudflare/go,nawawi/go,CAFxX/go,golang/go,cloudflare/go,nawawi/go,cloudflare/go,CAFxX/go,golang/go,cloudflare/go,golang/go,CAFxX/go,cloudflare/go,CAFxX/go,akutz/go,cloudflare/go,akutz/go,nawawi/go,nawawi/go,nawawi/go,akutz/go,CAFxX/go,CAFxX/go