ART: Clean up compiler

Clean up the compiler: less extern functions, dis-entangle
compilers, hide some compiler specifics, lower global includes.

Change-Id: Ibaf88d02505d86994d7845cf0075be5041cc8438
diff --git a/compiler/elf_patcher.cc b/compiler/elf_patcher.cc
index 9ae755d..72bf7d3 100644
--- a/compiler/elf_patcher.cc
+++ b/compiler/elf_patcher.cc
@@ -19,6 +19,7 @@
 #include <vector>
 #include <set>
 
+#include "class_linker.h"
 #include "elf_file.h"
 #include "elf_utils.h"
 #include "mirror/art_field-inl.h"