Make the server report monotonic times for deadlines

For very high performance systems, we're going to want to be able to
simply push the value reported from the server down onto clients.

If we report realtime now, then all wrapped languages are going to
assume it, meaning that such a change will be impossible later.
diff --git a/src/ruby/ext/grpc/rb_grpc.c b/src/ruby/ext/grpc/rb_grpc.c
index 829f825..65d9c9a 100644
--- a/src/ruby/ext/grpc/rb_grpc.c
+++ b/src/ruby/ext/grpc/rb_grpc.c
@@ -209,10 +209,12 @@
 /* Converts a wrapped time constant to a standard time. */
 static VALUE grpc_rb_time_val_to_time(VALUE self) {
   gpr_timespec *time_const = NULL;
+  gpr_timespec real_time;
   TypedData_Get_Struct(self, gpr_timespec, &grpc_rb_timespec_data_type,
                        time_const);
-  return rb_funcall(rb_cTime, id_at, 2, INT2NUM(time_const->tv_sec),
-                    INT2NUM(time_const->tv_nsec));
+  real_time = gpr_convert_clock_type(*time_const, GPR_CLOCK_REALTIME);
+  return rb_funcall(rb_cTime, id_at, 2, INT2NUM(real_time.tv_sec),
+                    INT2NUM(real_time.tv_nsec));
 }
 
 /* Invokes inspect on the ctime version of the time val. */