Land prep work to enable NaCl in the Linux x64 GN builds.

ppapi/native_client/src/untrusted/pnacl_support_extension/BUILD.gn

Index: ppapi/native_client/src/untrusted/pnacl_support_extension/BUILD.gn
diff --git a/ppapi/native_client/src/untrusted/pnacl_support_extension/BUILD.gn b/ppapi/native_client/src/untrusted/pnacl_support_extension/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..750e8ea3097d8f270e89ba6fbc93f827a0167a36
--- /dev/null
+++ b/ppapi/native_client/src/untrusted/pnacl_support_extension/BUILD.gn
@@ -0,0 +1,7 @@
+import("//build/config/features.gni")

[brettw, 2015/02/05 00:20:36]

Copyright (I'm going to stop commenting on these)

+
+if (enable_nacl && enable_nacl_untrusted && enable_pnacl) {

[Nick Bray (chromium), 2015/02/05 23:21:46]

Dito

[Dirk Pranke, 2015/02/05 23:52:19]

Will make same fix.

+  group("pnacl_support_extension") {
+    # TODO(dpranke): implement me ...
+  }
+}