Bug 666140: Error out if MOZCONFIG points to a non-existent file. r=khuey

build/autoconf/mozconfig-find

@@ -46,6 +46,15 @@
 #
 topsrcdir=$1
 
+for _config in "$MOZCONFIG" \
+               "$MOZ_MYCONFIG"
+do
+  if [ -n "$_config" ] && ! [ -f "$_config" ]; then
+    echo "Specified MOZCONFIG \"$_config\" does not exist!"
+    exit 1
+  fi
+done
+
 for _config in "$MOZCONFIG" \
                "$MOZ_MYCONFIG" \
                "$topsrcdir/.mozconfig" \