Add linux_clang to default try set so when one runs `git try` or `gcl try` it will add linux_clang automatically.
Add linux_clang to default try set so when one runs `git try` or `gcl try` it
will add linux_clang automatically.

TEST=Less tree breakage because of not trying changes on clang first.
BUG=None
NOTRY=true

Review URL: http://codereview.chromium.org/9395027

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@122041 0039d316-1c4b-4281-b951-d872f2087c98

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