Reduce stack usage for overflow checks

This reduces the stack space reserved for overflow checks to 12K, split
into an 8K gap and a 4K protected region.  GC needs over 8K when running
in a stack overflow situation.

Also prevents signal runaway by detecting a signal inside code that
resulted from a signal handler invokation.  And adds a max signal count to
the SignalTest to prevent it running forever.

Also reduces the number of iterations for the InterfaceTest as this was
taking (almost) forever with the --trace option on run-test.

Bug: 15435566

Change-Id: Id4fd46f22d52d42a9eb431ca07948673e8fda694
diff --git a/runtime/entrypoints_order_test.cc b/runtime/entrypoints_order_test.cc
index ae1b94f..f572d27 100644
--- a/runtime/entrypoints_order_test.cc
+++ b/runtime/entrypoints_order_test.cc
@@ -70,6 +70,10 @@
     EXPECT_OFFSET_DIFFP(Thread, tls32_, daemon, throwing_OutOfMemoryError, 4);
     EXPECT_OFFSET_DIFFP(Thread, tls32_, throwing_OutOfMemoryError, no_thread_suspension, 4);
     EXPECT_OFFSET_DIFFP(Thread, tls32_, no_thread_suspension, thread_exit_check_count, 4);
+    EXPECT_OFFSET_DIFFP(Thread, tls32_, thread_exit_check_count,
+                        is_exception_reported_to_instrumentation_, 4);
+    EXPECT_OFFSET_DIFFP(Thread, tls32_, is_exception_reported_to_instrumentation_,
+                        handling_signal_, 4);
 
     // TODO: Better connection. Take alignment into account.
     EXPECT_OFFSET_DIFF_GT3(Thread, tls32_.thread_exit_check_count, tls64_.trace_clock_base, 4,