Clear shutdown callchain after exec callbacks

ble/Gap.h

@@ -1047,6 +1047,7 @@ public:
     virtual ble_error_t reset(void) {
         /* Notify that the instance is about to shutdown */
         shutdownCallChain.call(this);
+        shutdownCallChain.clear();
 
         /* Clear Gap state */
         state.advertising = 0;

ble/GattClient.h

@@ -376,6 +376,7 @@ public:
     virtual ble_error_t reset(void) {
         /* Notify that the instance is about to shutdown */
         shutdownCallChain.call(this);
+        shutdownCallChain.clear();
 
         onDataReadCallbackChain.clear();
         onDataWriteCallbackChain.clear();

ble/GattServer.h

@@ -447,6 +447,7 @@ public:
     virtual ble_error_t reset(void) {
         /* Notify that the instance is about to shutdown */
         shutdownCallChain.call(this);
+        shutdownCallChain.clear();
 
         serviceCount = 0;
         characteristicCount = 0;

ble/SecurityManager.h

@@ -284,6 +284,7 @@ public:
     virtual ble_error_t reset(void) {
         /* Notify that the instance is about to shutdown */
         shutdownCallChain.call(this);
+        shutdownCallChain.clear();
 
         securitySetupInitiatedCallback = NULL;
         securitySetupCompletedCallback = NULL;