<Sound Dev> [9] Review Request: 8074831 Resolve disabled warnings for libjsound

[Sergey Bylokhov]

Hello.
Please review the fix for jdk9:
  - I "turn on warnings as error" for libjsound library.
  - The last warning was fixed. The problem was in fact that string 
literals should be "char const *" not  "char *"

Note that all new changes should be warning free, otherwise it will 
cause a build breakage.

Bug: https://bugs.openjdk.java.net/browse/JDK-8074831
Webrev can be found at: http://cr.openjdk.java.net/~serb/8074831/webrev.00

-- 
Best regards, Sergey.