Import WAMR Fast JIT (#1343)

Import WAMR Fast JIT which is a lightweight JIT with quick startup, small footprint,
relatively good performance (~40% to ~50% of LLVM JIT) and good portability.

Platforms supported: Linux, MacOS and Linux SGX.
Arch supported: x86-64.

core/iwasm/fast-jit/jit_utils.c

@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2021 Intel Corporation.  All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include "jit_utils.h"
+
+JitBitmap *
+jit_bitmap_new(uintptr_t begin_index, unsigned bitnum)
+{
+    JitBitmap *bitmap;
+
+    if ((bitmap = jit_calloc(offsetof(JitBitmap, map) + (bitnum + 7) / 8))) {
+        bitmap->begin_index = begin_index;
+        bitmap->end_index = begin_index + bitnum;
+    }
+
+    return bitmap;
+}