Merging r155902:

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r155902 | void | 2012-05-01 01:27:43 -0700 (Tue, 01 May 2012) | 7 lines

Change the PassManager from a reference to a pointer.

The TargetPassManager's default constructor wants to initialize the PassManager
to 'null'. But it's illegal to bind a null reference to a null l-value. Make the
ivar a pointer instead.
PR12468

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_31@155903 91177308-0d34-0410-b5e6-96231b3b80d8