Do not check arch for format check.

Use a generic check if the address is 32 bits when using the default
formating of a backtrace line instead of an arch check.

Test: New unit tests pass.
Change-Id: Id609abc037d7b437a02d52763aa91fbefe5f4d5b
diff --git a/libunwindstack/tests/RegsFake.h b/libunwindstack/tests/RegsFake.h
index 3c5af4a..b81b2ca 100644
--- a/libunwindstack/tests/RegsFake.h
+++ b/libunwindstack/tests/RegsFake.h
@@ -45,6 +45,8 @@
 
   void IterateRegisters(std::function<void(const char*, uint64_t)>) override {}
 
+  bool Format32Bit() { return false; }
+
   uint64_t GetAdjustedPc(uint64_t rel_pc, Elf*) override { return rel_pc - 2; }
 
   bool StepIfSignalHandler(uint64_t, Elf*, Memory*) override { return false; }