Currently targets that do not support selects with scalar conditions and vector operands - scalarize the code. ARM is such a target
because it does not support CMOV of vectors. To implement this efficientlyi, we broadcast the condition bit and use a sequence of NAND-OR
to select between the two operands. This is the same sequence we use for targets that don't have vector BLENDs (like SSE2).

rdar://12201387

llvm-svn: 162926