Merge pull request #7016 from mikaleppanen/async_dns_corr

Corrected asynchronous DNS functionality

Author: Cruz Monrreal

features/FEATURE_LWIP/lwip-interface/LWIPStack.cpp

@@ -209,7 +209,7 @@ void LWIP::tcpip_thread_callback(void *ptr)
 
 nsapi_error_t LWIP::call_in(int delay, mbed::Callback<void()> func)
 {
-    lwip_callback *cb = new lwip_callback;
+    lwip_callback *cb = new (std::nothrow) lwip_callback;
     if (!cb) {
         return NSAPI_ERROR_NO_MEMORY;
     }

features/netsocket/NetworkStack.cpp

@@ -114,7 +114,7 @@ nsapi_error_t NetworkStack::getsockopt(void *handle, int level, int optname, voi
 
 nsapi_error_t NetworkStack::call_in(int delay, mbed::Callback<void()> func)
 {
-    events::EventQueue *event_queue = mbed::mbed_event_queue();
+    static events::EventQueue *event_queue = mbed::mbed_event_queue();
 
     if (!event_queue) {
         return NSAPI_ERROR_NO_MEMORY;