make shell math operations style more succulent

Convert the style:
	var=$((${var} + 1))
to:
	: $(( var += 1 ))

The latter is easier to read imo.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

init.d/urandom.in

@@ -16,7 +16,7 @@ save_seed()
 	local psz=1
 
 	if [ -e /proc/sys/kernel/random/poolsize ]; then
-		psz=$(($(cat /proc/sys/kernel/random/poolsize) / 4096))
+		: $(( psz = $(cat /proc/sys/kernel/random/poolsize) / 4096 ))
 	fi
 
 	(	# sub shell to prevent umask pollution