[CFG] [analyzer] Add C++17-specific ctor-initializer construction contexts.

[CFG] [analyzer] Add C++17-specific ctor-initializer construction contexts.

CXXCtorInitializer-based constructors are also affected by the C++17 mandatory
copy elision, like variable constructors and return value constructors.
Extend r328248 to support those.

Differential Revision: https://reviews.llvm.org/D44763

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@328255 91177308-0d34-0410-b5e6-96231b3b80d8