RFR: 8211962: Implicit narrowing in MacOSX java.desktop jsound

[Kim Barrett]

[I'm not sure whether core-libs is the right list for java.desktop changes.] 

Please review this trivial fix of a build failure on MacOSX when
compiling with C++11/14 enabled. An int value is being used in an
initializer where an unsigned int is needed, which is not permitted
since C++11.  The solution taken is to cast the value in the
initializer.  A "better" solution would be to change the type of the
value, but that has substantial fannout because there are many places
in our code where signed ints were used instead of the unsigned ints
used by the underlying MacOSX framework.

CR:
https://bugs.openjdk.java.net/browse/JDK-8211962

Webrev:
http://cr.openjdk.java.net/~kbarrett/8211962/open.00/

Testing:
mach5 tier1 on MacOSX (really just verifying it builds).