Add native libraries to gn apks

build/config/android/config.gni

Index: build/config/android/config.gni
diff --git a/build/config/android/config.gni b/build/config/android/config.gni
index d7026d0a5c0252303509d8bbd9497c80e7ceb5f5..a0398b209a855649ada2c7b2a43d9baee7e0137d 100644
--- a/build/config/android/config.gni
+++ b/build/config/android/config.gni
@@ -87,18 +87,30 @@ if (is_android) {
   # only need to define the current one, rather than one for every platform
   # like the toolchain roots.
   if (cpu_arch == "x86") {
+    android_current_toolchain_root = x86_android_toolchain_root
+    android_prebuilt_arch = "android-x86"
+    binary_prefix = "i686-linux-android"
     android_libgcc_file =
       "$x86_android_toolchain_root/lib/gcc/i686-linux-android/${_android_toolchain_version}/libgcc.a"
   } else if (cpu_arch == "arm") {
+    android_current_toolchain_root = arm_android_toolchain_root
+    android_prebuilt_arch = "android-arm"
+    binary_prefix = "arm-linux-androideabi"
     android_libgcc_file =
       "$arm_android_toolchain_root/lib/gcc/arm-linux-androideabi/${_android_toolchain_version}/libgcc.a"
   } else if (cpu_arch == "mipsel") {
+    android_current_toolchain_root = mips_android_toolchain_root
+    android_prebuilt_arch = "android-mips"
+    binary_prefix = "mipsel-linux-android"
     android_libgcc_file =
       "$mips_android_toolchain_root/lib/gcc/mipsel-linux-android/${_android_toolchain_version}/libgcc.a"
   } else {
     assert(false, "Need android libgcc support for your target arch.")
   }
 
+  android_readelf = "$android_current_toolchain_root/bin/$binary_prefix-readelf"
+  android_gdbserver = "$android_ndk_root/prebuilt/$android_prebuilt_arch/gdbserver/gdbserver"
+
   # stlport stuff --------------------------------------------------------------
 
   use_system_stlport = is_android_webview_build