s390: Fix FunctionBodyDecoderTest to compile with gcc4.8.5

test/unittests/wasm/function-body-decoder-unittest.cc

Index: test/unittests/wasm/function-body-decoder-unittest.cc
diff --git a/test/unittests/wasm/function-body-decoder-unittest.cc b/test/unittests/wasm/function-body-decoder-unittest.cc
index ffac2637f1eb3b15a96c7ebdc1e91c2b254a96af..eb6b370b8c5e040eb4a6d10dcc312b55710f577a 100644
--- a/test/unittests/wasm/function-body-decoder-unittest.cc
+++ b/test/unittests/wasm/function-body-decoder-unittest.cc
@@ -1854,7 +1854,7 @@ TEST_F(FunctionBodyDecoderTest, BreakNesting_6_levels) {
 
       int depth = 6;
       int m = mask;
-      for (size_t pos = 0; pos < sizeof(code); pos++) {
+      for (size_t pos = 0; pos < sizeof(code) - 1; pos++) {
         if (code[pos] != kExprBlock) continue;
         if (m & 1) {
           code[pos] = kExprLoop;