gn: Support build directories outside the source tree.

tools/gn/binary_target_generator.cc

Index: tools/gn/binary_target_generator.cc
diff --git a/tools/gn/binary_target_generator.cc b/tools/gn/binary_target_generator.cc
index deee2161b58bfe89fa8652cce05c7a5b06305c06..74d4aca0da04d73f2a53b8af976d09d70ff777ac 100644
--- a/tools/gn/binary_target_generator.cc
+++ b/tools/gn/binary_target_generator.cc
@@ -9,6 +9,7 @@
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/scope.h"
+#include "tools/gn/settings.h"
 #include "tools/gn/value_extractors.h"
 #include "tools/gn/variables.h"
 
@@ -112,7 +113,8 @@ bool BinaryTargetGenerator::FillAllowCircularIncludesFrom() {
     return true;
 
   UniqueVector<Label> circular;
-  ExtractListOfUniqueLabels(*value, scope_->GetSourceDir(),
+  ExtractListOfUniqueLabels(scope_->settings()->build_settings(), *value,
+                            scope_->GetSourceDir(),
                             ToolchainLabelForScope(scope_), &circular, err_);
   if (err_->has_error())
     return false;