Merging r338751:

Merging r338751:
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r338751 | tstellar | 2018-08-02 20:16:10 +0200 (Thu, 02 Aug 2018) | 13 lines

CMake: Remove LLVM_DYLIB_SYMBOL_VERSIONING

Summary:
This option is no longer needed since r300496 added symbol
versioning by default

Reviewers: sylvestre.ledru, beanz, mgorny

Reviewed By: mgorny

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49835
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_70@338842 91177308-0d34-0410-b5e6-96231b3b80d8