Code review request: 8004235: Disable native JGSS provider on Mac

[Weijun Wang]

The native JGSS provider on Mac is not ready yet. Disable the native lib 
creation. Please review the code changes at

   http://cr.openjdk.java.net/~weijun/8004235/webrev.00/
*build-dev*: I don't know how to write 2 ifneq on a single line.

Thanks
Max