Remove the LIBS from platformsupport

The application / library that uses this should know it needs to link
to ie. udev, xrendr etc.

Change-Id: I9e3ffd4d98b3bd66abb8e621378b010da7feda7a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Laszlo Agocs <laszlo.p.agocs@nokia.com>

src/platformsupport/glxconvenience/glxconvenience.pri

@@ -1,6 +1,5 @@
 contains(QT_CONFIG,xlib):contains(QT_CONFIG,xrender) {
     contains(QT_CONFIG,opengl):!contains(QT_CONFIG,opengles2) {
-        LIBS += $$QMAKE_LIBS_X11 -lXrender
         HEADERS += $$PWD/qglxconvenience_p.h
         SOURCES += $$PWD/qglxconvenience.cpp
     }

src/platformsupport/udev/udev.pri

@@ -1,5 +1,4 @@
 contains(QT_CONFIG, libudev) {
     HEADERS += $$PWD/qudevhelper_p.h $$PWD/qudevicehelper_p.h
     SOURCES += $$PWD/qudevhelper.cpp $$PWD/qudevicehelper.cpp
-    LIBS += -ludev
 }