Pull in r217197 from upstream clang trunk (by Richard Smith):

Pull in r217197 from upstream clang trunk (by Richard Smith):

  PR20844: If we fail to list-initialize a reference, map to the
  referenced type before retrying the initialization to produce
  diagnostics. Otherwise, we may fail to produce any diagnostics, and
  silently produce invalid AST in a -Asserts build. Also add a note to
  this codepath to make it more clear why we were trying to create a
  temporary.

This should fix assertions when parsing some forms of incomplete list
intializers.

Direct commit to stable/9 and stable/10, since stable/11 and head
already have this upstream fix.

Reported by:	ajcbowhill@gmail.com
PR:		202665

git-svn-id: svn://svn.freebsd.org/base/stable/10@328555 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f