Summary:
Adds some basic building blocks to build hg using buck.
Header files are cleaned up, so they are relative to the project root.
Some minor changes to C code are made to remove clang build
warnings.
Rust dependencies, fb-hgext C/Python dependencies (ex. cstore,
mysql-connector), and 3rd-party dependencies like python-lz4
are not built yet. But the built hg binary should be able to run
most tests just fine.
Reviewed By: wez
Differential Revision: D6814686
fbshipit-source-id: 59eefd5a3ad86db2ad1c821ed824c9f1878c93e4
We mostly abide by this style.
In one case, a blank line was inserted to prevent a local
`#include "file"` from coming before a `#include <file>`.
Differential Revision: https://phab.mercurial-scm.org/D908