Delete thread key on process exit

[aggarg]

Description

Previously, the shared thread key was deleted in xPortStartScheduler after scheduler was ended. This created a race condition where prvThreadKeyDestructor (responsible for freeing thread-specific heap memory) would not be called if xPortStartScheduler deleted the key before the last task deletion, as destructors are not invoked after key deletion (see https://github.com/walac/glibc/blob/master/nptl/pthread_create.c#L145-L150).

Move thread key deletion to process exit to ensure all thread-specific memory is properly freed.

Test Steps

The LeakSanitzer reports leak without this change for the following program:

#include <FreeRTOS.h>
#include <task.h>

#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>

static StackType_t stack[4096];
static StaticTask_t task;
static TaskHandle_t taskHandle;

static void callback(void *unused)
{
    (void)unused;
    vTaskEndScheduler();
}

int main(void)
{
    taskHandle = xTaskCreateStatic(callback, "thread", 4096, NULL,
                      FREERTOS_PRIORITY_NORMAL, stack, &task);
    vTaskStartScheduler();
    vTaskDelete(taskHandle);
    return 0;
}

Checklist:

• I have tested my changes. No regression in existing tests.
• [NA] I have modified and/or added unit-tests to cover the code changes in this Pull Request.

Related Issue

https://forums.freertos.org/t/leaksanitizer-detects-memory-leaks-occasionally-in-gcc-posix/23387

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud