Remove warning lines from phing completion

Remove "Warning:" lines from phing targets list. Warning lines are
returned by phing when a target has no tasks or dependencies.

# Conflicts:
#	plugins/phing/phing.plugin.zsh

plugins/phing/phing.plugin.zsh

@@ -1,6 +1,6 @@
 _phing () {
   if [ -f build.xml ]; then
-    compadd $(phing -l|grep -v "\[property\]"|grep -v "Buildfile"|sed 1d|grep -v ":$" |grep -v "^\-*$"|awk '{print $1}')
+    compadd $(phing -l|grep -v "\[property\]"|grep -v "Buildfile"|sed 1d|grep -v ":$" |grep -v "^\-*$"|grep -v "Warning:"|awk '{print $1}')
   fi
 }