fate: use diff -b in oneline comparison

This is simpler and should take care of any problems with mixed
line ending styles.

Signed-off-by: Mans Rullgard <mans@mansr.com>

tests/fate-run.sh

@@ -61,9 +61,7 @@ stddev(){
 }
 
 oneline(){
-    val=$(cat "$2")
-    test x"$val" = x"$1" || { r=$?; printf -- '-%s\n+%s\n' "$ref" "$val"; }
-    return ${r:-0}
+    printf '%s\n' "$1" | diff -u -b - "$2"
 }
 
 run(){