Fix a bug handling nodes with variable arguments.  The code was fixed to assume that there were two input operands before the variable operand portion.  This *happened* to be true for all call instructions, which took a chain and a destination, but was not true for the PPC BCTRL instruction, whose destination is implicit.
Fix a bug handling nodes with variable arguments.  The code was fixed to assume
that there were two input operands before the variable operand portion.  This
*happened* to be true for all call instructions, which took a chain and a
destination, but was not true for the PPC BCTRL instruction, whose destination
is implicit.

Making this code more general allows elimination of the custom selection logic
for BCTRL.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@31732 91177308-0d34-0410-b5e6-96231b3b80d8

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