For building v8 using gn on aix_ppc64, linux_s390x and linux_ppc64(both LE and BE).

Also add support for host_byteorder logic which is introduced in -
https://codereview.chromium.org/2815453004/

R=adamk@chromium.org, dpranke@chromium.org, machenbach@chromium.org
BUG=706728

Review-Url: https://codereview.chromium.org/2812173002 .
diff --git a/BUILD.gn b/BUILD.gn
index 7c38dbb..e3d12f4 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/host_byteorder.gni")
 import("//third_party/icu/config.gni")
 
 if (is_android) {
@@ -984,8 +985,9 @@
 } else {
   data_dir = "common"
 }
-# TODO(GYP): Support to use host byteorder to select the icu date file
-if (current_cpu == "mips" || current_cpu == "mips64") {
+
+if (current_cpu == "mips" || current_cpu == "mips64" ||
+    host_byteorder == "big") {
   data_bundle_prefix = "icudtb"
 } else {
   data_bundle_prefix = "icudtl"