ART: More warnings

Enable -Wno-conversion-null, -Wredundant-decls and -Wshadow in general,
and -Wunused-but-set-parameter for GCC builds.

Change-Id: I81bbdd762213444673c65d85edae594a523836e5
diff --git a/runtime/stack.cc b/runtime/stack.cc
index 0adf031..4408609 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -409,8 +409,8 @@
 
 size_t StackVisitor::ComputeNumFrames(Thread* thread) {
   struct NumFramesVisitor : public StackVisitor {
-    explicit NumFramesVisitor(Thread* thread)
-        : StackVisitor(thread, NULL), frames(0) {}
+    explicit NumFramesVisitor(Thread* thread_in)
+        : StackVisitor(thread_in, NULL), frames(0) {}
 
     bool VisitFrame() OVERRIDE {
       frames++;
@@ -461,8 +461,8 @@
 
 void StackVisitor::DescribeStack(Thread* thread) {
   struct DescribeStackVisitor : public StackVisitor {
-    explicit DescribeStackVisitor(Thread* thread)
-        : StackVisitor(thread, NULL) {}
+    explicit DescribeStackVisitor(Thread* thread_in)
+        : StackVisitor(thread_in, NULL) {}
 
     bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
       LOG(INFO) << "Frame Id=" << GetFrameId() << " " << DescribeLocation();