Merging r315086:

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r315086 | compnerd | 2017-10-06 11:06:59 -0700 (Fri, 06 Oct 2017) | 8 lines

Bitcode: add an auto-upgrade for LTO section name

The bitcode reader looks specifically for `__DATA, __objc_catlist` as a
section name.  However, SVN r304661 removed the spaces (the two names
are functionally equivalent but do not compare equally
lexicographically).  This causes compatibility issues.  Add an
auto-upgrade path for removing the spaces as well as use the new name in
the LTO plugin.
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llvm-svn: 318851