Rewrite image type in CompilerOptions.

Prepare for introduction of boot image extension.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: Pixel 2 XL boots.
Change-Id: Id007c4aeb4ada84fe65c1148fdf67e8a412e5b74
diff --git a/compiler/dex/dex_to_dex_decompiler_test.cc b/compiler/dex/dex_to_dex_decompiler_test.cc
index 4f83d60..f61e6c4 100644
--- a/compiler/dex/dex_to_dex_decompiler_test.cc
+++ b/compiler/dex/dex_to_dex_decompiler_test.cc
@@ -41,7 +41,7 @@
   void CompileAll(jobject class_loader) REQUIRES(!Locks::mutator_lock_) {
     TimingLogger timings("CompilerDriverTest::CompileAll", false, false);
     TimingLogger::ScopedTiming t(__FUNCTION__, &timings);
-    compiler_options_->boot_image_ = false;
+    compiler_options_->image_type_ = CompilerOptions::ImageType::kNone;
     compiler_options_->SetCompilerFilter(CompilerFilter::kQuicken);
     // Create the main VerifierDeps, here instead of in the compiler since we want to aggregate
     // the results for all the dex files, not just the results for the current dex file.