Move implementations from class_root.h to -inl.h .

Make it possible to include the definition of enum ClassRoot
without pulling in a lot of other headers.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: aosp_taimen-userdebug boots.
Change-Id: Ic90fdd70bfe0c5428a5c9a0d7901ea7e15b03488
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 810871c..a5e0991 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -23,7 +23,7 @@
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "class_linker-inl.h"
-#include "class_root.h"
+#include "class_root-inl.h"
 #include "code_generator.h"
 #include "common_dominator.h"
 #include "intrinsics.h"