Pull in r361696 from upstream llvm trunk (by Sanjay Patel):
[SelectionDAG] soften assertion when legalizing narrow vector FP ops The test based on PR42010: https://bugs.llvm.org/show_bug.cgi?id=42010 ...may show an inaccuracy for PPC's target defs, but we should not be so aggressive with an assert here. There's no telling what out-of-tree targets look like.
This fixes an assertion when building the graphics/mesa-dri port for
Reported by: Mark Millard <firstname.lastname@example.org>