build: add simdutf dir to include path in GN build

The GN build defaults `node_simdutf_path` to `//third_party/simdutf`,
the copy that ships in a Chromium checkout. That target doesn't put
its own directory on the include path, so the unqualified
`#include "simdutf.h"` in libnode, node_js2c and node_cctest doesn't
resolve unless the embedder adds the directory themselves.

Add `get_label_info(node_simdutf_path, "dir")` to `node_internal_config`
(used by libnode and node_cctest) and to node_js2c's `include_dirs`.

Signed-off-by: Shelley Vohr <shelley.vohr@gmail.com>

Author: codebytere

unofficial.gni

@@ -81,6 +81,7 @@ template("node_gn_build") {
       "src/inspector:*",
     ]
     configs = [ ":node_external_config" ]
+    include_dirs = [ get_label_info(node_simdutf_path, "dir") ]
     libs = []
     cflags = [ "-Wno-microsoft-include" ]
     cflags_cc = [
@@ -337,7 +338,10 @@ template("node_gn_build") {
       "src/builtin_info.cc",
       "src/builtin_info.h",
     ]
-    include_dirs = [ "src" ]
+    include_dirs = [
+      "src",
+      get_label_info(node_simdutf_path, "dir"),
+    ]
   }
 
   action("run_node_js2c") {