Remove src/widgets/kernel/x11.pri.

Presumably, this was set for QSound, which has since moved to QtMultimedia (and
no longer uses nas, anyway).

Configure also no longer seems to have logic for setting nas, as of
4535913c4f.

Change-Id: Ie5b351844bd169ad0548b0d29513adbf6f5d9a12
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Donald Carr <donald.carr@nokia.com>
Reviewed-by: Girish Ramakrishnan <girish.1.ramakrishnan@nokia.com>

src/widgets/kernel/x11.pri

@@ -1,4 +0,0 @@
-x11 {
-        contains(QT_CONFIG, nas): LIBS_PRIVATE += -laudio -lXt
-}
- 

src/widgets/widgets.pro

@@ -23,7 +23,6 @@ include(../qbase.pri)
 contains(QT_CONFIG, x11sm):CONFIG += x11sm
 
 #platforms
-x11:include(kernel/x11.pri)
 mac:include(kernel/mac.pri)
 win32:include(kernel/win.pri)