formatting: run clang-format

[rsekman]

Many files in src/ and Tests/ were not formatted consistently according to the .clang-format in the repo. Perhaps this is because the .clang-format contained a duplicate entry that would cause clang-format to crash. This pull requests simply run

clang-format -i src/*.h src/*.c Tests/*.c{pp,} Tests/*.h

The files src/u8_lc_map.h src/u8_lc_map.c sj_to_unicode.c were excluded as the resulting diffs were extremely large.

I also tested running clang-format on all source files in plugins/ but the resulting diff is close to +500k/-500k.

[Oleksiy-Yakovenko]

It was not applied to the entire codebase intentionally, since it causes some unwanted changes.
I was trying to apply formatting over time to individual files, and improve the configuration file, but after some point I couldn't solve some problems and gave up.
For example, look how some tables are reformatted in junklib.c -- this causes a problem.
Unfortunately, I can't accept this PR -- if I could, I would have already reformatted the whole codebase myself.

[rsekman]

I understand.

Just FYI -- it is possible to exclude particular files with a .clang-format-ignore file and even parts of files from being reformatted by

// clang-format off: this code will not be reformatted
...
// clang-format on: reformatting resumes here