[libtooling] Add flag '-Xpreprocessor -detailed-preprocessing-record' by default in tests

Summary:
[libtooling] Add flag '-Xpreprocessor -detailed-preprocessing-record' by default in tests

This flag enables certain APIs related to preprocessing.

Test Plan: make -C libtooling test

Reviewers: irp, mehdi, mbolin

Reviewed By: mbolin

Differential Revision: https://phabricator.fb.com/D1448771
[clang-ocaml] Improve script yojson_validator.sh to deal with non-zipped files and standard json

Test plan:
make -C clang-ocaml test