[libclang] Make sure we don't ever leave a StoredDiagnostic associated with a SourceManager that has already been deleted, rdar://10768346.
[libclang] Make sure we don't ever leave a StoredDiagnostic associated with
a SourceManager that has already been deleted, rdar://10768346.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@149532 91177308-0d34-0410-b5e6-96231b3b80d8

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