Fix Bug 871 - Add optional xcode.clang support for all modules (Extends Bug 837 w/ xcode's xcrun)

Bump make/lib/cpptasks.jar to a65cc99054a5a6684784bf9a9e8c13fe866b81ad

make/lib/gluegen-clang.properties: Defaults to xcode.clang

make/jogamp-env.xml: Show env. SDKROOT