Add an option to disable native stack dumping on SIGQUIT.

Some of our (stress) run-tests do ANR dumping, which end up
stressing libunwind, that has known problems. To avoid getting
flakes due to libunwind, disable native stack dumping on SIGQUIT
for our run-tests.

bug:27185632
bug:24664297
Change-Id: I69085e48db903d6240448d71666ae2dcd091922e
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index da28da8..2aeb792 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -918,6 +918,7 @@
   is_explicit_gc_disabled_ = runtime_options.Exists(Opt::DisableExplicitGC);
   dex2oat_enabled_ = runtime_options.GetOrDefault(Opt::Dex2Oat);
   image_dex2oat_enabled_ = runtime_options.GetOrDefault(Opt::ImageDex2Oat);
+  dump_native_stack_on_sig_quit_ = runtime_options.GetOrDefault(Opt::DumpNativeStackOnSigQuit);
 
   vfprintf_ = runtime_options.GetOrDefault(Opt::HookVfprintf);
   exit_ = runtime_options.GetOrDefault(Opt::HookExit);