env/darwin/aws: don't quote extra args
env/darwin/aws: don't quote extra args

We do not want to quote $EXTRA_ARGS, as we explicitly want them split
into multiple arguments to qemu. This fixes start-installer.sh.

For golang/go#48945.

Change-Id: I6659f74120be534e9d909bcff85151011f8addd2
Reviewed-on: https://go-review.googlesource.com/c/build/+/432856
Run-TryBot: Michael Pratt <e7f1edc6d5aa9f6c8c377425db8f1a5816cbbb88@google.com>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/build,golang/build,golang/build,golang/build