Add missing newline symbol

to a test description file.

Author: petr-bauch

regression/cbmc-incr-oneloop/unwindset-more-loops1/test.desc

@@ -10,4 +10,4 @@ main.c
 ^Unwinding loop main\.3 iteration 3
 --
 ^warning: ignoring
-^Unwinding loop main\.0 iteration 6
+^Unwinding loop main\.0 iteration 6