AWTPrintLifecycle.setupPrint(..): Fix regression of commit a05b87a369441d9ef38f97929f866b3d4ced0e57: NULL printGLAD of GLCanvas and NewtCanvasAWT

We have to pre-init printGLAD w/ current GLAD (similiar w/ GLJPanel).

Also properly define reqNewGLAD:
   reqNewGLAD = !caps.getSampleBuffers() && ( reqNewGLADOnscrn || reqNewGLADSamples || reqNewGLADSize );

where '!caps.getSampleBuffers() && ( .. )' is due to Bug 830,
swapGLContextAndAllGLEventListener and onscreen MSAA w/ NV/GLX does not work.