ART: Delete old compiler_enums.h

Holdover from the Quick days. Move the two enums that are still
used closer to the actual users (and prune no longer used cases).

Test: m test-art-host
Change-Id: I88aa49961a54635788cafac570ddc3125aa38262
diff --git a/compiler/optimizing/instruction_builder.h b/compiler/optimizing/instruction_builder.h
index 9cfc065..517cf76 100644
--- a/compiler/optimizing/instruction_builder.h
+++ b/compiler/optimizing/instruction_builder.h
@@ -30,6 +30,8 @@
 
 namespace art {
 
+class Instruction;
+
 class HInstructionBuilder : public ValueObject {
  public:
   HInstructionBuilder(HGraph* graph,