[9] Review request: 8145604: Change minimum version of OS X SDK to 10.9

[Kevin Rushforth]

Please review the following change to the OS X build files to require a 
minimum version of SDK 10.9.

https://bugs.openjdk.java.net/browse/JDK-8145604
http://cr.openjdk.java.net/~kcr/8145604/webrev.01/

The bulk of the changes are in media, so anyone who wishes to test this 
should do:

gradle -PCOMPILE_MEDIA=true clean sdk

Thanks to Dave D for the media Makefile changes.

-- Kevin