Fix checkout location for naclports trybots.
Fix checkout location for naclports trybots.

The recent addition of alternate_url=, without also
setting name= was casuing the checkout to happen in
the wrong location.

This change brings the trybots inline with the buildbots
that set both name= and alternate_url=

R=bradnelson@google.com

Review URL: https://codereview.chromium.org/543883002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@291812 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build