Merging r217490:

Merging r217490:
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r217490 | delcypher | 2014-09-10 12:09:23 +0100 (Wed, 10 Sep 2014) | 4 lines

Don't attempt to run llvm-config in cmake/modules/Makefile when doing
``make clean`` because it won't be available.

This is an attempt to unbreak buildbots broken by r217484.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_35@217640 91177308-0d34-0410-b5e6-96231b3b80d8