Fixes the below error during do_configure:
../sources/xfce4-session-4.21.1/meson.build:50:21: ERROR: Program '/usr/bin/gdk-pixbuf-csource' not found or not executable
Signed-off-by: Mingli Yu <mingli.yu@windriver.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>