Remove the clang-tidy error used to trigger Travis CI error

Author: aheejin

src/passes/pass.cpp

@@ -698,10 +698,6 @@ void PassRunner::handleAfterEffects(Pass* pass, Function* func) {
 int PassRunner::getPassDebug() {
   static const int passDebug =
     getenv("BINARYEN_PASS_DEBUG") ? atoi(getenv("BINARYEN_PASS_DEBUG")) : 0;
-  int a = 0;
-  if (true)
-    a = 5;
-  (void)a;
   return passDebug;
 }