[SelectionDAG] Ensure constant folded legalized vector element types are...

[SelectionDAG] Ensure constant folded legalized vector element types are compatible with the BUILD_VECTOR type

Found during fuzz testing - 32-bit x86 targets were legalizing a <2 x i1> compare result to <2 x i32> when <2 x i64> was expected.

llvm-svn: 264085