WatchDog: remove coro stack size optimization

It was causing crashes on Android

src/util/watch_dog.h

@@ -95,31 +95,6 @@ public:
     void start(const asio::executor& ex, Duration d, OnTimeout on_timeout) {
         stop();
 
-        // This is defined in boost/libs/coroutine/src/{posix,windows}/stack_traits.cpp
-        // It seems to be defined to an arbitrary number 8*1024. I.e. it
-        // doesn't seem to be derived from sizes of some internal structures of
-        // the coroutine library.
-        size_t min_coro_size = boost::coroutines::stack_traits::minimum_size();
-
-        // XXX This is ugly, but given how often WatchDog is used, we do want to
-        // make the stack allocation small. Posslibly best approach would be to
-        // convert this whole class to use stackless coroutines in the future.
-        const size_t required_stack_size =
-                     ( sizeof(this)
-                     + sizeof(ex)
-                     + sizeof(d)
-                     + sizeof(asio::yield_context)
-                     + sizeof(HandlerTracker)
-                     + sizeof(State)
-                     + (sizeof(void*)*2) // ? Defer
-                     + sizeof(Clock::now())
-                     + sizeof(sys::error_code)
-                     ) * 2 // To account for temporaries
-                     + sizeof(on_timeout);
-
-        boost::coroutines::attributes attribs;
-        attribs.size = min_coro_size + required_stack_size;
-
         asio::spawn(ex, [self_ = this, ex, d, on_timeout = std::move(on_timeout)]
                          (asio::yield_context yield) mutable {
             TRACK_HANDLER();
@@ -143,7 +118,7 @@ public:
             }
 
             on_timeout();
-        }, attribs);
+        });
     }
 
     Clock::duration stop()