ls: fix coloring of dangling symlinks in default listing mode

ls: fix coloring of dangling symlinks in default listing mode

When listing a directory containing dangling symlinks,
and not outputting a long format listing, and orphaned links
are set to no coloring in LS_COLORS, then the symlinks
would get no color rather than reverting to the standard
symlink color.  The issue was introduced in v8.13-19-g84457c4

* src/ls.c (print_color_indicator): Use the standard method
to check if coloring is specified for orphaned symlinks.
The existing method would consider 'or=00' or 'or=0' as significant
in LS_COLORS. Even 'or=' was significant as in that case the
string='or=' and the length=0.  Also apply the same change
for missing symlinks for consistency.
(gobble_file): Remove the simulation of linkok, which is only
tested in print_color_indicator() which now handles this directly
by keying on the LS_COLORS values correctly.
* tests/misc/ls-misc.pl: Add a test case.
* THANKS: Add the reporter.
* NEWS: Mention the fix.
Reported-by: David Matei