Declare vApplicationMallocFailedHook function in task.h instead in each C heap file (#483)

vApplicationMallocFailedHook was declared in each Heap file. which forces users to declare it and can cause problems if the prototype of the function changes.

Co-authored-by: Pierre-Noel Bouteville <pnb990@gmail.com>

.github/lexicon.txt

@@ -2476,6 +2476,7 @@ vapplicationgetidletaskmemory
 vapplicationgettimertaskmemory
 vapplicationidlehook
 vapplicationirqhandler
+vapplicationmallocfailedhook
 vapplicationsetuptickinterrupt
 vapplicationsetupticktimerinterrupt
 vapplicationsetuptimerinterrupt

include/portable.h

@@ -188,6 +188,19 @@ size_t xPortGetMinimumEverFreeHeapSize( void ) PRIVILEGED_FUNCTION;
     #define vPortFreeStack       vPortFree
 #endif
 
+#if ( configUSE_MALLOC_FAILED_HOOK == 1 )
+
+/**
+ * task.h
+ * @code{c}
+ * void vApplicationMallocFailedHook( void )
+ * @endcode
+ *
+ * This hook function is called when allocation failed.
+ */
+    void vApplicationMallocFailedHook( void ); /*lint !e526 Symbol not defined as it is an application callback. */
+#endif
+
 /*
  * Setup the hardware ready for the scheduler to take control.  This generally
  * sets up a tick interrupt and sets timers for the correct tick frequency.

portable/MemMang/heap_1.c

@@ -118,7 +118,6 @@ void * pvPortMalloc( size_t xWantedSize )
     {
         if( pvReturn == NULL )
         {
-            extern void vApplicationMallocFailedHook( void );
             vApplicationMallocFailedHook();
         }
     }

portable/MemMang/heap_2.c

@@ -249,7 +249,6 @@ void * pvPortMalloc( size_t xWantedSize )
     {
         if( pvReturn == NULL )
         {
-            extern void vApplicationMallocFailedHook( void );
             vApplicationMallocFailedHook();
         }
     }

portable/MemMang/heap_3.c

@@ -71,7 +71,6 @@ void * pvPortMalloc( size_t xWantedSize )
     {
         if( pvReturn == NULL )
         {
-            extern void vApplicationMallocFailedHook( void );
             vApplicationMallocFailedHook();
         }
     }

portable/MemMang/heap_4.c

@@ -269,7 +269,6 @@ void * pvPortMalloc( size_t xWantedSize )
     {
         if( pvReturn == NULL )
         {
-            extern void vApplicationMallocFailedHook( void );
             vApplicationMallocFailedHook();
         }
         else

portable/MemMang/heap_5.c

@@ -279,7 +279,6 @@ void * pvPortMalloc( size_t xWantedSize )
     {
         if( pvReturn == NULL )
         {
-            extern void vApplicationMallocFailedHook( void );
             vApplicationMallocFailedHook();
         }
         else