tests: fix warning in tst-symlink

The compiler correctly warns that we can't fill 4097 bytes of an array
size 4096 (=PATH_MAX). I don't know why this code had 4097 in the first
place.

The test still passes with this fix, and the warning is gone.

Refs #976.

Signed-off-by: Nadav Har'El <[email protected]>
Message-Id: <[email protected]>

Author: nyh

tests/tst-symlink.cc

@@ -269,7 +269,7 @@ int main(int argc, char **argv)
     report(rc < 0, "symlink");
     report(error == ENAMETOOLONG, "ENAMETOOLONG expected 1");
 
-    fill_buf(path, 4097);
+    fill_buf(path, PATH_MAX);
     unlink(N1);
     rc = symlink(path, N1);
     error = errno;