disable --architectures, it breaks on armel livefs builders trying to build armhf targets

debian/changelog

@@ -1,3 +1,11 @@
+livecd-rootfs (2.79) UNRELEASED; urgency=low
+
+  * setting --architectures seems to have weird side effects on arm
+    (considering all but the buildd arch as foreign etc), disable it for a
+    testbuild...
+
+ -- Oliver Grawert <ogra@ubuntu.com>  Mon, 27 Aug 2012 16:04:30 +0200
+
 livecd-rootfs (2.78) quantal; urgency=low
 
   * revert the last change, i was not aware that unity-2d was also ripped out

live-build/auto/config

@@ -318,7 +318,6 @@ esac
 lb config noauto \
 	--mode ubuntu \
 	--distribution "$SUITE" \
-	--architectures "$ARCH" \
 	--bootstrap-keyring ubuntu-keyring \
 	--binary-images "$BINARY_IMAGES" \
 	--memtest "$MEMTEST" \