Merging r181299:
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r181299 | djasper | 2013-05-07 02:25:29 -0700 (Tue, 07 May 2013) | 5 lines

Fix clang-format emacs integration in last line.

Emacs seems to have a line that is just past the last character of the
buffers content. This needs to be handled specially so that clang-format
is not called with an invalid -offset.
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_33@181380 91177308-0d34-0410-b5e6-96231b3b80d8