The `vector.extract` folding patterns do not support 0-D vectors (actually, 0-D vector support couldn't even be implemented as a folding pattern as it would require replacing `vector.extract` with a `vector.extractelement` op). This patch is bailing out folding when 0-D vectors are found. Reviewed By: nicolasvasilache, hanchung Differential Revision: https://reviews.llvm.org/D151847