lua: fix fio.rmtree to work with non empty dirs

Fix 'fio.rmtree' to remove a non empty directories.
And update test.

Closes #3258

src/lua/fio.lua

@@ -382,8 +382,12 @@ fio.rmtree = function(path)
     for i, f in ipairs(ls) do
         local tmppath = fio.pathjoin(path, f)
         local st = fio.stat(tmppath)
-        if st and st:is_dir() then
-            st, err = fio.rmtree(tmppath)
+        if st then
+            if st:is_dir() then
+                st, err = fio.rmtree(tmppath)
+            else
+                st, err = fio.unlink(tmppath)
+            end
             if err ~= nil  then
                 return nil, err
             end

test/app/fio.result

@@ -413,6 +413,27 @@ fio.rmdir(dir2)
   - false
   - 'fio: No such file or directory'
 ...
+-- gh-3258 rmtree should remove directories with files
+fio.mktree('tmp2/tmp3/tmp4')
+---
+- true
+...
+fh = fio.open('tmp2/tmp3/tmp4/tmp.txt', {'O_RDWR', 'O_CREAT'})
+---
+...
+fh:close()
+---
+- true
+...
+fio.rmtree('tmp2')
+---
+- true
+...
+fio.stat('tmp2')
+---
+- null
+- 'fio: No such file or directory'
+...
 fio.rmdir(tmpdir)
 ---
 - true

test/app/fio.test.lua

@@ -131,6 +131,14 @@ fio.rmdir(dir2)
 
 { fio.unlink(file1), fio.unlink(file2), fio.unlink(file3), fio.unlink(file4) }
 { fio.unlink(file1), fio.unlink(file2), fio.unlink(file3), fio.unlink(file4) }
+
+-- gh-3258 rmtree should remove directories with files
+fio.mktree('tmp2/tmp3/tmp4')
+fh = fio.open('tmp2/tmp3/tmp4/tmp.txt', {'O_RDWR', 'O_CREAT'})
+fh:close()
+fio.rmtree('tmp2')
+fio.stat('tmp2')
+
 fio.rmdir(tmpdir)
 fio.rmdir(tmpdir)