build: don't duplicate rule for weston.desktop
build: don't duplicate rule for weston.desktop

dist_wayland_session_DATA will distribute and install src/weston.desktop, so the
definition of wayland_session_DATA which also installs src/weston.desktop will
result in the file being installed twice and (rarely) cause install to fail.

Spotted and fix by Roy Li <rongqing.li@windriver.com>.
Signed-off-by: Ross Burton <cd36ec7a67dfb8d589bc66b85fd0a6cf213f3854@intel.com>
Reviewed-By: Derek Foreman <2f97e0f0bc172406aab8ccd42dab54c95bab8759@osg.samsung.com>

jonnylamb/weston,kwm81/weston,Gnurou/weston,Fantu/compositor-spice,eyolfson/weston,xorgy/weston,krezovic/weston,Tarnyko/weston-xdg_surface_present,xorgy/weston,kwm81/weston,Fantu/compositor-spice,jonnylamb/weston,Tarnyko/weston-xdg_surface_present,Gnurou/weston,sir-murray/weston,giucam/weston,sir-murray/weston,Fantu/compositor-spice,udoprog/weston,eyolfson/weston,udoprog/weston,giucam/weston,krezovic/weston