[turbofan] Fix more -Wsign-compare warnings.

src/compiler/js-inlining-heuristic.cc

Index: src/compiler/js-inlining-heuristic.cc
diff --git a/src/compiler/js-inlining-heuristic.cc b/src/compiler/js-inlining-heuristic.cc
index 5c626d15c6efcb3f87baaa53bbcd258474385274..d6229c2d6467d4b26776ca2d018e792934af87c7 100644
--- a/src/compiler/js-inlining-heuristic.cc
+++ b/src/compiler/js-inlining-heuristic.cc
@@ -23,7 +23,7 @@ namespace {
 
 int CollectFunctions(Node* node, Handle<JSFunction>* functions,
                      int functions_size) {
-  DCHECK_NE(0u, functions_size);
+  DCHECK_NE(0, functions_size);
   HeapObjectMatcher m(node);
   if (m.HasValue() && m.Value()->IsJSFunction()) {
     functions[0] = Handle<JSFunction>::cast(m.Value());