Added mi_visit_blocks to visit all blocks of all heaps in a thread

[DV-AG]

Added a method "mi_visit_blocks()" in src/heap.c to visit all blocks of all heaps in a thread and made required changes in include/mimalloc.h by adding

mi_decl_export bool mi_visit_blocks(const mi_heap_t* heap ,bool visit_blocks, mi_block_visit_fun* visitor, void* arg);

Below is the function I added

bool mi_visit_blocks(const mi_heap_t* heap, bool visit_blocks, mi_block_visit_fun* visitor, void* arg) {
  mi_assert_internal(heap != NULL);
  if (heap == NULL) return false;
  mi_heap_t* curr = heap->tld->heaps;
  while (curr != NULL) {
    mi_heap_t* next = curr->next;
    if(!mi_heap_visit_blocks(curr, visit_blocks, visitor, arg)){
      return false;
    }
    curr = next;
  }
  return true;
}

This function was tested with the below code

#include <stdio.h>
#include <stdlib.h>
#include "mimalloc.h"

static int block_count = 0;


bool visit_block(const mi_heap_t* heap,
                 const mi_heap_area_t* area,
                 void* block,
                 size_t block_size,
                 void* arg)
{
    block_count++;
    printf("Visited block %p size=%zu\n", block, block_size);
    return true;   // continue visiting
}

int main() {

    
    mi_heap_t* heap = mi_heap_new();

    if (heap == NULL) {
        printf("heap creation failed\n");
        return 1;
    }

    
    void* p1 = mi_heap_malloc(heap, 64);
    void* p2 = mi_heap_malloc(heap, 128);
    void* p3 = mi_heap_malloc(heap, 256);

    printf("Allocated blocks: %p %p %p\n", p1, p2, p3);

   
    mi_visit_blocks(heap, true, visit_block, NULL);

    printf("Total blocks visited: %d\n", block_count);

    /* cleanup */
    mi_free(p1);
    mi_free(p2);
    mi_free(p3);

    mi_heap_destroy(heap);

    return 0;
}

[DV-AG]

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[DV-AG]

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[DV-AG]

Fixes #1180