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/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 6ac7a31..90d7c35 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -760,16 +760,16 @@
     // the comparison and its condition as the branch condition.
     Register lhs = InputRegisterAt(condition, 0);
     Operand rhs = InputOperandAt(condition, 1);
-    Condition cond = ARM64Condition(condition->GetCondition());
-    if ((cond == eq || cond == ne) && rhs.IsImmediate() && (rhs.immediate() == 0)) {
-      if (cond == eq) {
+    Condition arm64_cond = ARM64Condition(condition->GetCondition());
+    if ((arm64_cond == eq || arm64_cond == ne) && rhs.IsImmediate() && (rhs.immediate() == 0)) {
+      if (arm64_cond == eq) {
         __ Cbz(lhs, true_target);
       } else {
         __ Cbnz(lhs, true_target);
       }
     } else {
       __ Cmp(lhs, rhs);
-      __ B(cond, true_target);
+      __ B(arm64_cond, true_target);
     }
   }