Make test_compression a little more forgiving

The retune of compression levels makes this test fail. This is due
to a few approximations used in the encoder that determine which
LP coefficient should result in the smallest file. Differences are
usually very small, but in my case this resulted in compression
level 6 giving a 3 byte bigger file.

This patch lets the compression test pass even if the a compression
level results in a file that is up to 10 byte larger than the
previous level

Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>

test/test_compression.sh

@@ -39,7 +39,7 @@ for k in 0 1 2 3 4 5 6 7 8 ; do
 		echo "Error : Compression ${last_k} size $last_size >= compression $k size $size."
 		exit 1
 		fi
-	last_size=${size}
+	let last_size=${size}+10
 	last_k=${k}
 	rm -f ${fname}
 	done