Merge branch 'lo/sparse-universal-zero-init'

Merge branch 'lo/sparse-universal-zero-init'

We've adopted a convention that any on-stack structure can be
initialized to have zero values in all fields with "= { 0 }", even
when the first field happens to be a pointer, but sparse complained
that a null pointer should be spelled NULL for a long time.  Start
using -Wno-universal-initializer option to squelch it.

* lo/sparse-universal-zero-init:
  sparse: allow '{ 0 }' to be used without warnings