add <ardour-root>/bin to PATH

prepare for video-util deployment in Linux bundle

tools/linux_packaging/ardour.sh.in

@@ -31,6 +31,9 @@ if [ ! -d $USER_ARDOUR_DIR ] ; then
     mkdir -p $USER_ARDOUR_DIR || exit 1
 fi
 
+PATH="${BIN_DIR}:${PATH}"
+export PATH
+
 # this triggers code in main() that will reset runtime environment variables
 # to point to directories inside the ardour package