Verify that phi instructions refer to MBBs in the CFG.
Verify that phi instructions refer to MBBs in the CFG.

The machine code verifier no longer tolerates phi instructions with noop
operands. All MBBs on a phi instruction must be in the CFG.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@82448 91177308-0d34-0410-b5e6-96231b3b80d8

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