add error messages for failures

scripts/xul2xhtml.sh

@@ -7,6 +7,7 @@ hg clone https://hg.mozilla.org/comm-central/ /tmp/comm-xul$$ || ERROR=1
 if [ $ERROR -eq 1 ]
 then
   rm -rf /tmp/*$$
+  echo "failed to clone comm-central"
   exit 1
 fi
 if [ '$GIT_REPO' != '' ]
@@ -17,6 +18,7 @@ then
   if [ $ERROR -eq 1 ]
   then
     rm -rf /tmp/*$$
+    echo "failed to clone git patch queue"
     exit 1
   fi
   cd /tmp/comm-xul$$
@@ -32,6 +34,7 @@ then
       if [ $ERROR -eq 1 ]
       then
         rm -rf /tmp/*$$
+        echo "failure applying $i"
         exit 1
       fi
     done