Make uncrustify.sh compatible with more recent env

recent mktemp wants template in gmxuncrust.XXXXX format
also canonical *nix based which doesnt have -s arg

Change-Id: Ic054c4eef3d4a49b7bae96b1012ec323a347567d
Signed-off-by: Alexey Shvetsov <alexxy@omrb.pnpi.spb.ru>