Fix warnings due to smaller datatypes

src/bitmap/bitmap_free.c

@@ -70,7 +70,7 @@ void bitmap_free(bitmap_rb_t *raw_block, void *ptr) {
     systemallocator.dmm_stats.num_free++;
 #endif /* WITH_ALLOCATOR_STATS */
 
-    cell_no = ((char *)chunk_header -
+    cell_no = (size_t) ((char *)chunk_header -
             ((char *)raw_block + sizeof(bitmap_rb_t) + 
              raw_block->elements * BMAP_EL_SIZE))
         / raw_block->bytes_per_cell;
@@ -79,7 +79,7 @@ void bitmap_free(bitmap_rb_t *raw_block, void *ptr) {
 
     size_t mask_counter = cells_used;
     size_t mask_start = cell_no % BMAP_EL_SIZE_BITS + 1;
-    unsigned int vector_index = cell_no / BMAP_EL_SIZE_BITS;
+    size_t vector_index = cell_no / BMAP_EL_SIZE_BITS;
 
     while(mask_counter != 0) {
         if(mask_counter > BMAP_EL_SIZE_BITS) {