[PATCH] In LICM, don't create more than one copy of an instruction per loop exit block when sinking.

[hfinkel at anl.gov]

Please make sure that you include the explanation from the PR (starting with "The problem is in LICM::sink, which does not handle the following pattern well:") into the commit message.  LGTM.

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Comment at: test/Transforms/LICM/extra-copies.ll:36
@@ +35,2 @@
+
+!0 = metadata !{metadata !"clang version 3.5.0 (211262)"}
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Please remove the extra metadata (like this one), and any unneeded attributes.

http://reviews.llvm.org/D4252