Before this patch, the result code was a mixture of `int` and
`CURLcode`.
Also adjust casts and fix a couple of minor issues found along the way.
Cherry-picked from #13489Closes#13600
all s3 requests default to UNSIGNED-PAYLOAD and add the required
x-amz-content-sha256 header. this allows CURLAUTH_AWS_SIGV4 to correctly
sign s3 requests to amazon with no additional configuration
Signed-off-by: Casey Bodley <cbodley@redhat.com>
Closes#9995