test: remove assertion in fs_statfs test

The f_files value can equal 0, making the current assertion
incorrect. Including 0 in the assertion range leads to a
type-limits compiler warning. So, this commit just removes
the redundant assertion.

Fixes: https://github.com/libuv/libuv/issues/2417
PR-URL: https://github.com/libuv/libuv/pull/2426
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>

test/test-fs.c

@@ -354,7 +354,7 @@ static void statfs_cb(uv_fs_t* req) {
   ASSERT(stats->f_files == 0);
   ASSERT(stats->f_ffree == 0);
 #else
-  ASSERT(stats->f_files > 0);
+  /* There is no assertion for stats->f_files that makes sense, so ignore it. */
   ASSERT(stats->f_ffree <= stats->f_files);
 #endif
   uv_fs_req_cleanup(req);