jbc2mpl need to support OpenJDK

In order to support the open source ark compiler and runtime environment, we need to support compiling OpenJDK jar files, at least the libcore.  While the latest version of OpenJDK is 14, we take version 8 as example here and jbc2mpl team could decide which versions to support.

1. if your system does not have hg, install it:
```sudo apt-get install mercurial```

2. if your make is version 4 or newer, likely need downgrade to 3.82 to build OpenJDK.  Get it from here:
```https://ftp.gnu.org/gnu/make/make-3.82.tar.gz```

3. get OpenJDK source:
```hg clone http://hg.openjdk.java.net/jdk8/jdk8 openjdk8```

4. modify Makefile to support newer OS (ubuntu 16.4):
openjdk8/hotspot/make/linux/Makefile
```
--- a/make/linux/Makefile       Tue Mar 04 11:51:03 2014 -0800
+++ b/make/linux/Makefile       Mon Jan 27 13:47:29 2020 -0800
@@ -225,7 +225,7 @@
 # Solaris 2.5.1, 2.6).
 # Disable this check by setting DISABLE_HOTSPOT_OS_VERSION_CHECK=ok.
 
-SUPPORTED_OS_VERSION = 2.4% 2.5% 2.6% 3%
+SUPPORTED_OS_VERSION = 2.4% 2.5% 2.6% 3% 4% 5%
 OS_VERSION := $(shell uname -r)
 EMPTY_IF_NOT_SUPPORTED = $(filter $(SUPPORTED_OS_VERSION),$(OS_VERSION))
```
5. follow the steps to build (refer to openjdk8/README). you might need to install a few required packages.
```
cd openjdk8
sh ./get_source.sh
bash ./configure
make -k LOG=debug
```

@TigerLuo86 FYI, here is what Ed ran into, same as my experience.

Hi Wen,

I'm running into problem using jbc2mpl to build OpenJDK java runtime. The following sums up the problem. Kindly comment if this matches what you saw and whether you were able to progress further with using jb2cmpl to compile OpenJDK java runtime.

------------------------------------------

One of the requirements to open source Maple is using OpenJDK's (i.e. rt.jar for OpenJDK8, or the java.* modules for OpenJDK9) instead of AOSP.
 
We need to use jbc2mpl to generate MapleIR directly from Java byte code.
However the current version of jb2cmpl that we downloaded from OpenArkCompiler, works ok when compiling AOSP's libcore byte code, but fails in compiling OpenJDK byte codes:
```
==================================================
Case 1: jbc2mpl failure with OpenJDK 8 build

eching@figo72:~/OpenJDK$ ~/jbc2mpl -injar openjdk8/build/linux-x86_64-normal-server-release/images/lib/rt.jar -out rt
Tid(57405): CHECK/CHECK_FATAL failure: false at [../../../jbc2mpl/src/jbcOpcode.cpp:138] Reversed opcode jsr

==================================================
Case 2: jbc2mpl failure with OpenJDK 9 build

#!/bin/bash
#classes to include in jar file
#run this from <openjdk9>/build/linux-x86_64-normal-server-release/jdk/modules
CLASSES=" \
java.base/sun \
java.base/jdk \
java.base/javax \
java.base/java \
java.base/com"
# create jar bundle
jar cvf classes.jar $CLASSES
# generate mpl
~/jbc2mpl -injar classes.jar -out classes

Tid(23571): CHECK/CHECK_FATAL failure: false at [../../../jbc2mpl/src/fe_stmt_util.cpp:85] Unsupported type: 
==================================================
```

We need to have these OpenJDK byte code compile errors resolved in jbc2mpl, either binary or buildable source (in open source framework) to be able to properly open source Maple.

目前是不行的，没有公开依赖包是libcore时候我试过（将近一个月之后的时候官方才开金口）……
如果确实要做，可以把rt等.jar中不涉及jsr保留字的.class打成一个.jar，然后就jbc2mpl可以处理通过惹，但是前提是你机器的内存最少要32G（不要问我是怎么知道的……）这个有可能算是bug，似乎是把所有.class中的依赖关系都直接丢到内存里得到的……
通过jbc2mpl把得到.jar包处理通过后，会得到对应的.mplt文件
但是在用这个java jdk（我用的oracle版的，原理上区别应该不大，对照你的报错结果看起来也是一致的）处理后的.mplt一同编译hello等程序时，你会发现居然会出现非法的指针访问，这是代码中某些地方没有检测指针的合法性（https://gitee.com/harmonyos/OpenArkCompiler/issues/I11S4R），而这解析过程出错，刚好说明它目前就没考虑什么java jdk，而仅限于那个libcore……
就算你编译过了，你会发现你得到的.s根本没法链接，因为他们自己做的链接器（过程）压根没公开，所以你无法得到那个mapleclasses.so……
就算你得到了mapleclasses.so，短时间内也无法用上x86等版的runtime，而是目前宣称的在x86上通过模拟arm的方法来跑的maple engine
那么问题又来了，模拟能反映出性能的提升吗？大概率不能。有没有提升呢？用emui 9.1以及往后的版本自己试试吧（一些关键进程确实编译成了maple化的应用形式，不过目前没有第三方maple化的app流出）……问了问实际手机环境中，方舟环境性能提升如何，回复曰：部分情景。（脑补一下表情吧~）
配套的鸿蒙在电视里拆不出来的，具体不好说。手机里的鸿蒙目前就是那个teeos，前好几年就存在了，这次算作是鸿蒙的一种雏形了，其实这次就是加上了形式化验证，保证安全性，因为之前被人爆菊几次了，这次是为了物联网的安全做基础，但是实际内部是什么样子没有消息（除了官方也不会有人敢曝）……
总结起来就是：最快三月份再看，否则基本就是浪费时间，我已经浪费了近半年时间了……
就算是三月份maple环境基本开源，也别期望过大，对一般人也没什么意义，跟opengeuler差不多，华为这套东西主要都是绕着arm转的，目前，一般人除了手机谁会玩儿arm平台呢？而且emui 10之后权限管理很严，想玩儿也玩儿不了，就是凑个热闹罢了……
不是我说，倒是google那边的Fuchsia与Dart与oracle的graal有点儿火候了，当然，人家也是很早就起步了……

GVP 方舟编译器/OpenArkCompiler

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GVP方舟编译器/OpenArkCompiler

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