Move build_config.h from chromium/base/build to chromium/base

Moved build_config.h to mimic the include path on ChromeOS and Brillo.
On those platform, this file is included as just "build/build_config.h"

Change-Id: Ia8a30299cc7f485b38eeeddef2e5210644b3d2a3
Reviewed-on: https://weave-review.googlesource.com/1811
Reviewed-by: Vitaly Buka <vitalybuka@google.com>
diff --git a/third_party/chromium/base/time/time_posix.cc b/third_party/chromium/base/time/time_posix.cc
index 2825ce5..e8e56c2 100644
--- a/third_party/chromium/base/time/time_posix.cc
+++ b/third_party/chromium/base/time/time_posix.cc
@@ -16,8 +16,8 @@
 #include <ostream>
 
 #include "base/basictypes.h"
-#include "base/build/build_config.h"
 #include "base/logging.h"
+#include "build/build_config.h"
 
 namespace {