webos_qmake5: Add bbclass

webOS specific variables for Qt. These will be used by individual
Qt componenets to install libraries, plugins and headers to correct
locations

Open-webOS-DCO-1.0-Signed-off-by: Mikko Levonmaa <mikko.levonmaa@palm.com>

Change-Id: I9620ff75c835297937fd838209524c5e34b758a5
Reviewed-on: https://g2g.palm.com/1657
Reviewed-by: Build Verification
Reviewed-by: Herb Kuta <herb.kuta@lge.com>
Reviewed-by: Mikko Levonmaa <mikko.levonmaa@palm.com>
Tested-by: Mikko Levonmaa <mikko.levonmaa@palm.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>