Fix crash in source-line truncation code for diagnostic printing. Also, when we only need to truncate the line at the end, make sure there is room for the ellipsis.
Fix crash in source-line truncation code for diagnostic
printing. Also, when we only need to truncate the line at the end,
make sure there is room for the ellipsis.



git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@70781 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang