Fix GN os, cpu defaults for Android builds.

tools/relocation_packer/config.gni

Index: tools/relocation_packer/config.gni
diff --git a/tools/relocation_packer/config.gni b/tools/relocation_packer/config.gni
index 90e3979337b420166c0723a20137b8172bf09227..4cdd9455b3e00db2c31e9f740771cd17e52b528b 100644
--- a/tools/relocation_packer/config.gni
+++ b/tools/relocation_packer/config.gni
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-relocation_packing_supported = target_arch == "arm" || target_arch == "arm64"
+relocation_packing_supported = target_cpu == "arm" || target_cpu == "arm64"
 
 if (relocation_packing_supported) {
   relocation_packer_target = "//tools/relocation_packer($host_toolchain)"
@@ -10,9 +10,9 @@ if (relocation_packing_supported) {
       get_label_info("$relocation_packer_target", "root_out_dir")
   relocation_packer_exe = "${relocation_packer_dir}/relocation_packer"
 
-  if (target_arch == "arm") {
+  if (target_cpu == "arm") {
     relocations_have_addends = 0
-  } else if (target_arch == "arm64") {
+  } else if (target_cpu == "arm64") {
     relocations_have_addends = 1
   }
 } else {