A few more c++ test examples

Summary: Add more c++ tests

Test Plan: make test

Reviewers: mathieubaudet

Reviewed By: mathieubaudet

Differential Revision: https://phabricator.fb.com/D1408738

Tasks: 3964417
Fix typo in .arcconfig

Summary: Fix typo in .arcconfig

Test Plan: bla

Differential Revision: https://phabricator.fb.com/D1421221
[ASTExporter] Support CXXNamedCastExpr

Summary:
[ASTExporter] Support CXXNamedCastExpr

This is an example diff based on the code discussed with @irp.

One important difference: I decided to follow the class hierarchy of clang more precisely than the original code of ASTDumper.
More precisely:
- VisitCXXNamedCastExpr calls VisitCastExpr
- VisitCastExpr takes care of the 'base path' and the 'cast kind' : this code benefits VisitCXXNamedCastExpr.

In a next iteration (e.g. to add CXXFunctionalCastExpr) we _might_ want to go further, that is, define VisitExplicitCastExpr and make VisitCXXNamedCastExpr call it instead of VisitCastExpr, to factorize 'qual_type'.

Test Plan:
make -C libtooling test
make -C clang-ocaml test

Reviewers: ddino, irp

Reviewed By: irp

Subscribers: irp

Differential Revision: https://phabricator.fb.com/D1410633

Tasks: 3964417
Use bash script yojson_validator.sh instead of ocaml code

Summary:
Use bash script yojson_validator.sh instead of ocaml code

I found one example where clang_ast_yojson_validator would hang in case of error. This is annoying. Let us piggy-back on the 'converters' and use a trivial bash script.

Test Plan: make -C clang-ocaml test

Reviewers: irp

Reviewed By: irp

Subscribers: mathieubaudet

Differential Revision: https://phabricator.fb.com/D1410628

Tasks: 3964417
[doc] Update prerelease notes
make tests pass

Summary: 'make test' was failing for me on libtooling, so I re-recorded them, and added a simple one for the "this" keyword because the next construction I'm looking at is CXXThisExpr

Test Plan: make -C libtooling/ test

Reviewers: mathieubaudet

Reviewed By: mathieubaudet

Differential Revision: https://phabricator.fb.com/D1428719

Tasks: 3964417
[clang-ocaml] fix test (forgot to remove one old target)

Summary: [clang-ocaml] fix test (forgot to remove one old target)

Test plan: make -C clang-ocaml clean test