Proposing to return scalar function when VF==1.

I am adding trivial mapping scalar --> scalar when VF==1 to

prevent false positive for "isVectorizable" query. Also modified

"getVectorizedFunction" to return scalar function when VF==1.

This patch is supported by LIT and unit tests.

I think it is worth describing this method making sure it is clear it realizes the VFShape of the original scalar function with VF =1, something like this.