It's cool, but making it standalone is slightly simpler and means license is
pure MIT.

Ben Hutchings points out that struct sockaddr isn't large enough to hold
a struct sockaddr_in6.  Our example works because we only access the family
field, but anyone extending it might be surprised; use a union instead.

This can happen if the documentation doesn't have a properly formatted summary line,
and it causes the examples_relevant test to segfault.

Brad Hards fixed a two places where score->error was not \n-terminated,
and then I found a few more, so make it automatic.

This confuses the output, and makes us sometimes see spurious
failure.  At least we will still catch valgrind errors in
children of failtest, thanks to --error-exitcode=101.

Reordering header makes it more readable, and we don't rely on
getopt_long any more.

Two places were using a bogus ccanlint struct: the side-effect was
that valgrind options didn't work, nor did license fixups.

Make REGISTER_TEST do the extern declaration, and remove the bogus
ones.

You can use talloc_array_length() to get the length of a tallocated array.

I originally called this talloc_length(), but SAMBA upstream uses
talloc_array_length.

Use this to preserve the entire working directory.

It leads to numerous problems, such as the next ccanlint getting confused
trying to compile examples, and "-k examples_compile -k examples_exist"
giving bogus errors.

So instead we leave the temporary dir lying around and delete
individual files which aren't marked "keep".

Otherwise valgrind will report that tests leak memory.

This makes some cases simpler, where you no longer want malloc etc.
to fail.

Looks like the example was copy-n-pasted from the previous entry.

Brad suggested this after finding one such cut & paste in str:

rusty@vivaldi:~/devel/cvs/ccan/ccan/str$ ../../tools/ccanlint/ccanlint
Example: sections demonstrate appropriate function (examples_relevant): FAIL
/home/rusty/devel/cvs/ccan/ccan/str/str.h:64:Example for strcount doesn't mention it
Total score: 37/38

Before:
	$ tools/ccanlint/ccanlint -d ccan/talloc/
	Module's source code has no trailing whitespace (no_trailing_whitespace): FAIL
	: Total score: 0/1

After:
	$ tools/ccanlint/ccanlint -d ccan/talloc/
	Module's source code has no trailing whitespace (no_trailing_whitespace): FAIL
	talloc: Total score: 0/1

We simply build up the error string in score_file_error; a bit different
but simpler than current behaviour.  We keep around struct file_error
because some tests need it.

My refactoring introduced a bug: we need to set score=1 for the success case.

With the original layout, we got:
Summary:
An efficient allocator for blocks that don't need to be
....
Description:
resized or freed.

Makes reporting of documentation easier.