Fixes incompatibility with an Arch update by foregrounding cdm's call to startx

After an arch update, backgrounding the call to startx no longer worked. This
problem is referenced in the Arch Linux forums:
https://bbs.archlinux.org/viewtopic.php?pid=1413023

src/cdm-xlaunch

@@ -87,9 +87,9 @@ fi
 
 if $altstartx; then
     # Alternative method of calling setsid(/startx) for systems that are unresponsive to the 'normal' call.
-    (setsid startx "$@" > "$startxlog" 2>&1 &)
+    (setsid startx "$@" > "$startxlog" 2>&1)
 else
-    setsid startx "$@" > "$startxlog" 2>&1 &
+    setsid startx "$@" > "$startxlog" 2>&1
 fi
 
 # If wait(1) returns with a value >128, it was interrupted by kill(1),