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/compiler_specific.h b/third_party/chromium/base/compiler_specific.h
index 8c2ba34..63297dc 100644
--- a/third_party/chromium/base/compiler_specific.h
+++ b/third_party/chromium/base/compiler_specific.h
@@ -5,7 +5,7 @@
 #ifndef BASE_COMPILER_SPECIFIC_H_
 #define BASE_COMPILER_SPECIFIC_H_
 
-#include "base/build/build_config.h"
+#include "build/build_config.h"
 
 #if defined(COMPILER_MSVC)