tests/indent: clean up comments

indent: remove backslash line continuation outside preprocessing

The indenter did not handle these backslashes well, interpreting them as
unary operators, and they are an edge case anyway. Line continuations
in string literals and character constants are kept.

tests/indent: change directive from '#' to '//'

Using a '//' instead of '#' turns the directives into well-formed C
code, resulting in fewer error markers in the editor.

indent: remove FreeBSD IDs

Most of the IDs were empty anyway.

tests/indent: refine and extend tests

indent: remove support for pre-1978 variable initialization

tests/indent: migrate a few more tests to t_options

tests/indent: change directive from '#' to '//'

Using a '//' instead of '#' turns the directives into well-formed C
code, resulting in fewer error markers in the editor.

indent: remove FreeBSD IDs

Most of the IDs were empty anyway.

tests/indent: refine and extend tests

indent: remove support for pre-1978 variable initialization

tests/indent: migrate a few more tests to t_options

indent: remove FreeBSD IDs

Most of the IDs were empty anyway.

tests/indent: refine and extend tests

indent: remove support for pre-1978 variable initialization

tests/indent: migrate a few more tests to t_options