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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155902 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/Passes.h

@@ -56,7 +56,7 @@ public:
 
 protected:
   TargetMachine *TM;
-  PassManagerBase ±
+  PassManagerBase *PM;
   PassConfigImpl *Impl; // Internal data structures
   bool Initialized;     // Flagged after all passes are configured.