fix preferences

autogen.sh

@@ -3,4 +3,4 @@
 # object tree, but this will do if you have all parts of the required
 # tool-chain installed
 autoreconf -f -i || { echo "autoreconf failed: $?"; exit 1; }
-find . -name '*-private.h' -o -name '*-protos.h' -delete
+find . \( -name '*-private.h' -o -name '*-protos.h' \) -delete