Unreviewed build fix after r174477.

Unreviewed build fix after r174477.

* init-database.sql: Removed build_commits_index since it's redundant with build_commit's primary key.
Also fixed a syntax error that we were missing "," after line that declared build_commit column.

* public/api/runs.php: Fixed the query so that test_runs without commits data will be retrieved.
This is necessary for baseline and target values manually added via admin pages.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@174486 268f45cc-cd09-0410-ab3c-d52691b4dbfc