[Sema] Suppress warnings for C's zero initializer
Patch by S. Gilles!
Differential Revision: https://reviews.llvm.org/D28148
Pull in r314838 from upstream clang trunk (by Richard Smith):
Suppress -Wmissing-braces warning when aggregate-initializing a
struct with a single field that is itself an aggregate.
In C++, such initialization of std::array<T, N> types is guaranteed
to work by the standard, is completely idiomatic, and the "suggested"
alternative from Clang was technically invalid.
Together, these suppress unneeded "suggest braces around initialization
of subobject" warnings for C++11 initializer lists.
MFC after: 3 days
55f46b3c87