[Cronet] Suffix maven directory with arch

This prevents builders of different archs from overwriting each
other.

Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester
Change-Id: I5a1e88601e0872e51282d52bb5151fcedd02ab3b
Reviewed-on: https://chromium-review.googlesource.com/1042354Reviewed-by: Andrei Kapishnikov <kapishnikov@chromium.org>
Commit-Queue: Paul Jensen <pauljensen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555789}

components/cronet/android/BUILD.gn

@@ -1593,7 +1593,7 @@ group("cronet_test_package") {
   }
 }
 
-_maven_dir = "$_package_dir/maven"
+_maven_dir = "$_package_dir/maven-$current_cpu"
 _maven_modules_dir = "$_maven_dir/org/chromium/net"
 _maven_test_dir = "$_maven_dir/test"