[NaCl SDK] Add initial support for building the SDK with gn

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index ce698a7e0d1d15907bcc6e2063a5a81ea3206876..b0d678bce4f355b0252c28a023c4c6eec86a7878 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -722,9 +722,6 @@ group("gn_only") {
         "//third_party/libjpeg_turbo:simd_asm",
       ]
     }
-    if (enable_nacl) {
-      deps += [ "//native_client/src/trusted/service_runtime:sel_ldr" ]
-    }
     if (use_ozone) {
       deps += [ "//ui/ozone/demo" ]
     }
@@ -734,6 +731,10 @@ group("gn_only") {
     }
   }
 
+  if (enable_nacl) {
+    deps += [ "//native_client_sdk/src:nacl_core_sdk" ]
+  }
+
   if (is_android) {
     deps += [
       "//build/android/gyp/test:hello_world",