Implement proper support for generating code for compound literals in

Implement proper support for generating code for compound literals in
C++, which means:
  - binding the temporary as needed in Sema, so that we generate the
  appropriate call to the destructor, and
  - emitting the compound literal into the appropriate location for
  the aggregate, rather than trying to emit it as a temporary and
  memcpy() it.

Fixes PR10138 / <rdar://problem/9615901>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133235 91177308-0d34-0410-b5e6-96231b3b80d8