ports/unix: Add wasi VARIANT.

Start from a copy of standard.

Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com>

ports/unix/variants/wasi/manifest.py

@@ -0,0 +1,3 @@
+include("$(PORT_DIR)/variants/manifest.py")
+
+include("$(MPY_DIR)/extmod/asyncio")

ports/unix/variants/wasi/mpconfigvariant.h

@@ -0,0 +1,31 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// Set base feature level.
+#define MICROPY_CONFIG_ROM_LEVEL (MICROPY_CONFIG_ROM_LEVEL_EXTRA_FEATURES)
+
+// Enable extra Unix features.
+#include "../mpconfigvariant_common.h"

ports/unix/variants/wasi/mpconfigvariant.mk

@@ -0,0 +1,3 @@
+# This is the default variant when you `make` the Unix port.
+
+FROZEN_MANIFEST ?= $(VARIANT_DIR)/manifest.py