Move most of runtime/base to libartbase/base

Enforce the layering that code in runtime/base should not depend on
runtime by separating it into libartbase.  Some of the code in
runtime/base depends on the Runtime class, so it cannot be moved yet.
Also, some of the tests depend on CommonRuntimeTest, which itself needs
to be factored (in a subsequent CL).

Bug: 22322814
Test: make -j 50 checkbuild
      make -j 50 test-art-host

Change-Id: I8b096c1e2542f829eb456b4b057c71421b77d7e2
diff --git a/runtime/elf_file.h b/runtime/elf_file.h
index b1c9395..ab9e6fa 100644
--- a/runtime/elf_file.h
+++ b/runtime/elf_file.h
@@ -21,9 +21,9 @@
 #include <string>
 
 #include "base/macros.h"
+#include "base/os.h"
 // Explicitly include our own elf.h to avoid Linux and other dependencies.
 #include "./elf.h"
-#include "os.h"
 
 namespace art {
 template <typename ElfTypes>