os/exec: gofmt
os/exec: gofmt

CL 109361 introduced some changes which were not properly gofmt'ed.
Because the CL was sent via Github no gofmt checks were performed
on it (cf. #24946, #18548).

Change-Id: I207065f01161044c420e272f4fd112e0a59be259
Reviewed-on: https://go-review.googlesource.com/115356
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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