[Android] Make cpu_features dependent on configurable android_ndk_root

build/secondary/third_party/android_tools/BUILD.gn

Index: build/secondary/third_party/android_tools/BUILD.gn
diff --git a/build/secondary/third_party/android_tools/BUILD.gn b/build/secondary/third_party/android_tools/BUILD.gn
index ac754d2ec115bb71f51140592f03a6a4dd5ec7a0..ea1533f1950700ce127b530a33b0cfcd994c3604 100644
--- a/build/secondary/third_party/android_tools/BUILD.gn
+++ b/build/secondary/third_party/android_tools/BUILD.gn
@@ -5,7 +5,7 @@
 import("//build/config/android/rules.gni")
 
 config("cpu_features_include") {
-  include_dirs = [ "ndk/sources/android/cpufeatures" ]
+  include_dirs = [ "$android_ndk_root/sources/android/cpufeatures" ]
 }
 
 config("cpu_features_warnings") {
@@ -19,7 +19,7 @@ config("cpu_features_warnings") {
 # //build/android/ndk.gyp:cpu_features
 source_set("cpu_features") {
   sources = [
-    "ndk/sources/android/cpufeatures/cpu-features.c",
+    "$android_ndk_root/sources/android/cpufeatures/cpu-features.c",
   ]
   public_configs = [ ":cpu_features_include" ]