AIX: Work around for malloc(0) behavior

test/cctest/wasm/wasm-run-utils.h

Index: test/cctest/wasm/wasm-run-utils.h
diff --git a/test/cctest/wasm/wasm-run-utils.h b/test/cctest/wasm/wasm-run-utils.h
index fe9bbe9a2f55fa03c0b489b16304e91941ce1fb8..27fd586fd51d8d4e448cdb852af2fa643eb214be 100644
--- a/test/cctest/wasm/wasm-run-utils.h
+++ b/test/cctest/wasm/wasm-run-utils.h
@@ -110,7 +110,7 @@ class TestingModule : public ModuleEnv {
     CHECK_EQ(0, instance->mem_size);
     module_.has_memory = true;
     instance->mem_start = reinterpret_cast<byte*>(malloc(size));
-    CHECK(instance->mem_start);
+    CHECK(size == 0 || instance->mem_start);
     memset(instance->mem_start, 0, size);
     instance->mem_size = size;
     return raw_mem_start<byte>();