NFC: use array init instead of memset

Dropped the change from my previous CL which bisecting Windows failure.

R= titzer@chromium.org

Review URL: https://codereview.chromium.org/1760243002

Cr-Commit-Position: refs/heads/master@{#34512}

src/wasm/module-decoder.cc

@@ -51,8 +51,7 @@ class ModuleDecoder : public Decoder {
     module->mem_external = false;
     module->origin = origin_;
 
-    bool sections[kMaxModuleSectionCode];
-    memset(sections, 0, sizeof(sections));
+    bool sections[kMaxModuleSectionCode] = {false};
 
     const byte* pos = pc_;
     uint32_t magic_word = consume_u32("wasm magic");