This fixes two bugs:

* Issue #728 where git_status_file was not working for files
  that contain spaces.  This was caused by reusing the "fnmatch"
  parsing code from ignore and attribute files to interpret the
  "pathspec" that constrained the files to apply the status to.
  In that code, unescaped whitespace was considered terminal to
  the pattern, so a file with internal whitespace was excluded
  from the matched files.  The fix was to add a mode to that code
  that allows spaces and tabs inside patterns.  This mode only
  comes into play when parsing in-memory strings.

* The other issue was undetected, but it was in the recently
  added code to reload gitattributes / gitignores when they were
  changed on disk.  That code was not clearing out the old values
  from the cached file content before reparsing which meant that
  newly added patterns would be read in, but deleted patterns
  would not be removed.  The fix was to clear the vector of
  patterns in a cached file before reparsing the file.

This updates to the latest clar which includes the helpers
`cl_assert_equal_s` and `cl_assert_equal_i`.  Convert the code
over to use those and remove the old libgit2-only helpers.

This migrates odb.c, odb_loose.c, odb_pack.c and pack.c to
the new style of error handling.  Also got the unix and win32
versions of map.c.  There are some minor changes to other
files but no others were completely converted.

This also contains an update to filebuf so that a zeroed out
filebuf will not think that the fd (== 0) is actually open
(and inadvertently call close() on fd 0 if cleaned up).

Lastly, this was built and tested on win32 and contains a
bunch of fixes for the win32 build which was pretty broken.