Clean up include paths

Remove runtime/globals.h and make clients point to the right globals.h
(libartbase/base/globals.h).  Also make within-libartbase includes
relative rather than using base/, etc.

Bug: 22322814
Test: make -j 40 checkbuild
Change-Id: I99de63fc851d48946ab401e2369de944419041c7
diff --git a/libartbase/base/allocator.h b/libartbase/base/allocator.h
index 662f78e..5eb6ea6 100644
--- a/libartbase/base/allocator.h
+++ b/libartbase/base/allocator.h
@@ -19,8 +19,8 @@
 
 #include <type_traits>
 
-#include "base/atomic.h"
-#include "base/macros.h"
+#include "atomic.h"
+#include "macros.h"
 
 namespace art {