[Parse] Forward brace locations to TypeConstructExpr

When parsing C++ type construction expressions with list initialization,
forward the locations of the braces to Sema.

Without these locations, the code coverage pass crashes on the given test
case, because the pass relies on getLocEnd() returning a valid location.

Here is what this patch does in more detail:

  - Forwards init-list brace locations to Sema (ParseExprCXX),
  - Builds an InitializationKind with these locations (SemaExprCXX), and
  - Uses these locations for constructor initialization (SemaInit).

The remaining changes fall out of introducing a new overload for
creating direct-list InitializationKinds.

Testing: check-clang, and a stage2 coverage-enabled build of clang with
asserts enabled.

Differential Revision: https://reviews.llvm.org/D41921

llvm-svn: 322729