[8u60] RFR: 8043340: [macosx] Fix hard-wired paths to JavaVM.framework

[David DeHaven]

> The --with-xcode-path argument is optional, you should also be able to build with Xcode 4 selected via "sudo xcode-select -switch /path/to/Xcode4.app". I leave MAS managed Xcode (currently 6) active as I'm constantly bouncing between projects and it's a hassle to have to remember to reset the active toolchain, so I thought it best to allow configure to be provided a path.

Ugh. I broke something along the way, this doesn't *quite* work.

xcrun complains with "xcrun: error: missing DEVELOPER_DIR path:"

I think I'm exporting an empty DEVELOPER_DIR. I shall fix and update.

-DrD-