Stop propagation of dependent configs between toolchains.

tools/gn/target.cc

Index: tools/gn/target.cc
diff --git a/tools/gn/target.cc b/tools/gn/target.cc
index 4430512877d033109fb9afaef859fb3b8fad1e8a..759d7bff14493e59663830c67f2259562eb28f11 100644
--- a/tools/gn/target.cc
+++ b/tools/gn/target.cc
@@ -352,8 +352,10 @@ bool Target::OnResolved(Err* err) {
   // private deps. This step re-exports them as public configs for targets that
   // depend on this one.
   for (const auto& dep : public_deps_) {
-    public_configs_.Append(dep.ptr->public_configs().begin(),
-                           dep.ptr->public_configs().end());
+    if (dep.ptr->toolchain() == toolchain()) {
+      public_configs_.Append(dep.ptr->public_configs().begin(),
+                             dep.ptr->public_configs().end());
+    }
   }
 
   // Copy our own libs and lib_dirs to the final set. This will be from our
@@ -502,10 +504,17 @@ bool Target::GetOutputFilesForSource(const SourceFile& source,
 }
 
 void Target::PullDependentTargetConfigs() {
-  for (const auto& pair : GetDeps(DEPS_LINKED))
-    MergeAllDependentConfigsFrom(pair.ptr, &configs_, &all_dependent_configs_);
-  for (const auto& pair : GetDeps(DEPS_LINKED))
-    MergePublicConfigsFrom(pair.ptr, &configs_);
+  for (const auto& pair : GetDeps(DEPS_LINKED)) {
+    if (pair.ptr->toolchain() == toolchain()) {
+      MergeAllDependentConfigsFrom(pair.ptr, &configs_,
+                                   &all_dependent_configs_);
+    }
+  }
+  for (const auto& pair : GetDeps(DEPS_LINKED)) {
+    if (pair.ptr->toolchain() == toolchain()) {
+      MergePublicConfigsFrom(pair.ptr, &configs_);
+    }
+  }
 }
 
 void Target::PullDependentTargetLibsFrom(const Target* dep, bool is_public) {