Add newline at end of test file.

As requested by @shajrawi in #16545.

Author: gottesmm

test/SILOptimizer/predictable_memopt.sil

@@ -880,4 +880,4 @@ bb0(%arg : $K):
   %4 = load %0 : $*SWithOpt
   dealloc_stack %0 : $*SWithOpt
   return %4 : $SWithOpt
-}
+}