First steps in implementing DR1467: List-initialization of aggregate from same-type object.

Only the first two items for now, changing Sections 8.5.4 [dcl.init.list] paragraph 3 and 13.3.1.7 [over.match.list] paragraph 1,
so that defining class objects and character arrays using uniform initialization syntax is actually treated as list initialization
and before it is treated aggregate initialization.

llvm-svn: 227022