dump_constants: Also dump the arch name

This change also dumps the arch name. This will be useful in the second
version of the minijail policy syntax.

Bug: None
Test: ./dump_constants

Change-Id: I4fe2b4f0ec52121ecdb6c7b312b6afaa62d3b36c
diff --git a/dump_constants.cc b/dump_constants.cc
index f33bd5b..4603809 100644
--- a/dump_constants.cc
+++ b/dump_constants.cc
@@ -17,6 +17,7 @@
 int main() {
   std::cout << "{\n";
   std::cout << "  \"arch_nr\": " << ARCH_NR << ",\n";
+  std::cout << "  \"arch_name\": \"" << ARCH_NAME << "\",\n";
   std::cout << "  \"bits\": " << (sizeof(uintptr_t) * 8) << ",\n";
   std::cout << "  \"syscalls\": {\n";
   bool first = true;