Remove duplicate source file
Remove duplicate source file

${SPECIFIC_OS_FILES} already includes this file for X11 platforms. This gets
rid of a warning when running cmake.

pankajp/pyside,enthought/pyside,enthought/pyside,enthought/pyside,qtproject/pyside-pyside,PySide/PySide,BadSingleton/pyside2,gbaty/pyside2,gbaty/pyside2,RobinD42/pyside,IronManMark20/pyside2,PySide/PySide,M4rtinK/pyside-bb10,BadSingleton/pyside2,pankajp/pyside,RobinD42/pyside,pankajp/pyside,M4rtinK/pyside-bb10,BadSingleton/pyside2,enthought/pyside,enthought/pyside,IronManMark20/pyside2,qtproject/pyside-pyside,qtproject/pyside-pyside,M4rtinK/pyside-bb10,enthought/pyside,gbaty/pyside2,M4rtinK/pyside-bb10,M4rtinK/pyside-android,IronManMark20/pyside2,PySide/PySide,M4rtinK/pyside-android,enthought/pyside,BadSingleton/pyside2,RobinD42/pyside,gbaty/pyside2,M4rtinK/pyside-android,RobinD42/pyside,IronManMark20/pyside2,PySide/PySide,M4rtinK/pyside-android,gbaty/pyside2,BadSingleton/pyside2,pankajp/pyside,qtproject/pyside-pyside,qtproject/pyside-pyside,IronManMark20/pyside2,M4rtinK/pyside-android,M4rtinK/pyside-android,pankajp/pyside,PySide/PySide,M4rtinK/pyside-bb10,RobinD42/pyside,M4rtinK/pyside-bb10,RobinD42/pyside,RobinD42/pyside