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