Fix build bot after r340598.
Fix build bot after r340598.

Revert to the original behavior: only calculate real file path when
file is opened and avoid using InterndPath for real path calculation.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@340602 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 6093fea79d46ed6f9846e7f069317ae996149c69)

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang