Add command line support for enabling the optimizing compiler.

Also run tests with the optimizing compiler enabled when
the file art/USE_OPTIMIZING_COMPILER is present.

Change-Id: Ibc33eed62a43547bc3b9fe786d014c0d81b5add8
diff --git a/compiler/llvm/compiler_llvm.cc b/compiler/llvm/compiler_llvm.cc
index 4ce714a..2812700 100644
--- a/compiler/llvm/compiler_llvm.cc
+++ b/compiler/llvm/compiler_llvm.cc
@@ -39,7 +39,7 @@
 
 namespace art {
 void CompileOneMethod(CompilerDriver& driver,
-                      CompilerBackend* compilerBackend,
+                      Compiler* compiler,
                       const DexFile::CodeItem* code_item,
                       uint32_t access_flags, InvokeType invoke_type,
                       uint16_t class_def_idx, uint32_t method_idx, jobject class_loader,
@@ -142,7 +142,7 @@
   cunit->SetCompilerDriver(compiler_driver_);
   // TODO: consolidate ArtCompileMethods
   CompileOneMethod(*compiler_driver_,
-                   compiler_driver_->GetCompilerBackend(),
+                   compiler_driver_->GetCompiler(),
                    dex_compilation_unit->GetCodeItem(),
                    dex_compilation_unit->GetAccessFlags(),
                    invoke_type,