wamr-python: Enable debugging WASM and grant dir access (#2449)

- Enable debugging a WASM loaded and executed from Python.
- Expose API to enable access to list of host directories. Similar to --dir in iwasm.
- Add another python language binding sample: native-symbol.

language-bindings/python/wamr-api/samples/basic/compile.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# Copyright (C) 2019 Intel Corporation.  All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+/opt/wasi-sdk/bin/clang     \
+    -O0 -z stack-size=4096 -Wl,--initial-memory=65536 \
+    -Wl,--strip-all,--no-entry -nostdlib \
+    -Wl,--export=sum\
+    -Wl,--allow-undefined \
+    -o sum.wasm sum.c

language-bindings/python/wamr-api/samples/basic/main.py

@@ -0,0 +1,22 @@
+# Copyright (C) 2019 Intel Corporation.  All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+from wamr.wamrapi.wamr import Engine, Module, Instance, ExecEnv
+from ctypes import c_uint
+import pathlib
+
+def main():
+    engine = Engine()
+    module = Module.from_file(engine, pathlib.Path(__file__).parent / "sum.wasm")
+    module_inst = Instance(module)
+    exec_env = ExecEnv(module_inst)
+
+    func = module_inst.lookup_function("sum")
+
+    argv = (c_uint * 2)(*[10, 11])
+    exec_env.call(func, len(argv), argv)
+    print(argv[0])
+
+
+if __name__ == "__main__":
+    main()

language-bindings/python/wamr-api/samples/basic/sum.c

@@ -0,0 +1,12 @@
+/*
+ * Copyright (C) 2019 Intel Corporation.  All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include <stdio.h>
+
+int
+sum(int a, int b)
+{
+    return a + b;
+}