message: EDSC: fix unused-wariable warning when compiling without assertions
  In LowerEDSCTestPass, there are two range-for loops that only do assertions on
  the loop variable.  With assertions disabled, the variable becomes unused and
  triggers a warning promoted to error.  Cast it to void in the loop to supress
  the warning.
diff: @@ -51,9 +51,11 @@ PassResult LowerEDSCTestPass::runOnFunction(Function *f) {
  FuncBuilder builder(&f->getBlocks().front(),
  f->getBlocks().front().begin());
  assert(f->getNumArguments() == 2 && "dynamic_for expected 4 arguments");
  - for (const auto *arg : f->getArguments())
  + for (const auto *arg : f->getArguments()) {
  + (void)arg;
  assert(arg->getType().isIndex() &&
  "dynamic_for expected index arguments");
  + }
  edsc::ScopedEDSCContext context;
  edsc::Expr lb, ub, step;
  @@ -73,9 +75,11 @@ PassResult LowerEDSCTestPass::runOnFunction(Function *f) {
  FuncBuilder builder(&f->getBlocks().front(),
  f->getBlocks().front().begin());
  assert(f->getNumArguments() == 4 && "dynamic_for expected 4 arguments");
  - for (const auto *arg : f->getArguments())
  + for (const auto *arg : f->getArguments()) {
  + (void)arg;
  assert(arg->getType().isIndex() &&
  "dynamic_for expected index arguments");
  + }
  edsc::ScopedEDSCContext context;
  edsc::Expr lb1, lb2, ub1, ub2, step;
  