Summary:
Adds the option for required features to container definitions. These cause the container not to be passed to `DrgnParser` if that feature is not enabled during code generation. The thrift isset type does not currently work with `tree-builder-v2` and only provides benefit with `capture-thrift-isset`. This change makes sure the container is ignored if it won't be useful, allowing code generation under `tree-builder-v2`.
Test Plan: - CI
Differential Revision: D49960512
Pulled By: JakeHillion
These represent types which don't store any interesting data for us to
measure, but which are required by a real container so can not be
replaced with our own generated class types.
std::allocator often has bad DWARF, so it must be replaced after the
DWARF is fixed up in Flattener. The others could be replaced earlier in
the transformation process if desired, but I've left them all together
for simplicity for now.
This fixes the folly::fbstring tests.