RFR: 8216154: C4819 warnings at HotSpot sources on Windows

[Yasumasa Suenaga]

Hi all,

Please review this change:

   JBS: https://bugs.openjdk.java.net/browse/JDK-8216154
   webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8216154/webrev.00/
   Discussion on build-dev: https://mail.openjdk.java.net/pipermail/build-dev/2019-January/024581.html


I tried to build OpenJDK on WSL (Windows 10 1809 + VS2017 (15.9.4) + Ubuntu 18.04 LTS).
However, I saw some C4819 warnings as below:

```
c:/OpenJDK/jdk/src/hotspot/share/compiler/methodMatcher.cpp(258): warning C4819: ファイルは、現在のコード ページ (0) で表示できない文字を含んでいます。データの損失を防ぐために、ファイルを Unicode 形式で保存してください。
```

* The locale of my laptop is set to Japanese (CP932)

I saw this warning at 2 files as below:

   - hotspot/share/code/codeHeapState.cpp
   - hotspot/share/compiler/methodMatcher.cpp

We can see the problem with iconv:
   $ iconv -f US-ASCII -t UTF8 <file>


This change passed submit repo tests.


Thanks,

Yasumasa