Remove ArtCode.

- Instead use OatQuickMethodHeader.
- Various cleanups now that we don't have all those
  ArtMethod -> ArtCode -> OatQuickMethodHeader indirections.

As a consequence of this cleanup, exception handling got a bit
faster.

ParserCombinators benchmark (exception intensive) on x64: (lower is better)
Before:
ParserCombinators(RunTime): 1062500.0 us.
After:
ParserCombinators(RunTime): 833000.0 us.

Change-Id: Idac917b6f1b0dc254ad68fb3781cd61bccadb0f3
diff --git a/runtime/Android.mk b/runtime/Android.mk
index 8fe3fa2..9236ffb 100644
--- a/runtime/Android.mk
+++ b/runtime/Android.mk
@@ -19,7 +19,6 @@
 include art/build/Android.common_build.mk
 
 LIBART_COMMON_SRC_FILES := \
-  art_code.cc \
   art_field.cc \
   art_method.cc \
   atomic.cc.arm \
@@ -156,6 +155,7 @@
   oat_file.cc \
   oat_file_assistant.cc \
   oat_file_manager.cc \
+  oat_quick_method_header.cc \
   object_lock.cc \
   offsets.cc \
   os_linux.cc \