configure: add hint of libfdt to DTC dependency not found message Most distros package it as libfdt, and mentioning libfdt here makes it much easier to find the package you're missing. Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com> Reviewed-by: Stefan Weil <sw@weilnetz.de> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>