fixup! dir.c: regression fix for add_excludes with fscache

It is unlikely that the fstat() call fails, but not impossible...
Coverity pointed out that we check for its return value elsewhere, so we
might just as well do it here, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

dir.c

@@ -788,8 +788,10 @@ static int add_excludes(const char *fname, const char *base, int baselen,
			fd = open(fname, O_RDONLY);
			if (fd < 0)
				warn_on_fopen_errors(fname);
			if (S_ISLNK(st.st_mode))
				fstat(fd, &st);
			if (S_ISLNK(st.st_mode) && fstat(fd, &st) < 0) {
				warn_on_fopen_errors(fname);
				fd = -1;
			}
		}
	} else {
		fd = open(fname, O_RDONLY);