Introduce a 'baseline' variant for the compiler.

Implemented as a stripped down version of the optimizing compiler,
not running any optimization.

Adjust code to still work with expectations in code generators.

bug: 111397239

Test: test.py --baseline
Change-Id: I4328283825f9a890616e7496ed4c1e77d6bcc5dd
diff --git a/compiler/driver/compiler_options.h b/compiler/driver/compiler_options.h
index 34aceba..e9cbf74 100644
--- a/compiler/driver/compiler_options.h
+++ b/compiler/driver/compiler_options.h
@@ -193,6 +193,10 @@
     return boot_image_;
   }
 
+  bool IsBaseline() const {
+    return baseline_;
+  }
+
   // Are we compiling a core image (small boot image only used for ART testing)?
   bool IsCoreImage() const {
     // Ensure that `core_image_` => `boot_image_`.
@@ -346,6 +350,7 @@
   bool boot_image_;
   bool core_image_;
   bool app_image_;
+  bool baseline_;
   bool debuggable_;
   bool generate_debug_info_;
   bool generate_mini_debug_info_;