BitTracker.h needs a full definition of MachineInstr, so include the defining file.
BitTracker.h needs a full definition of MachineInstr, so include the defining file.

Patch by Dean Sturtevant!

Differential Revision: https://reviews.llvm.org/D42907

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@324245 91177308-0d34-0410-b5e6-96231b3b80d8

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