After commit f92b9ebed03dbd140a5a7b921cb898e661a59068, I am unable to allocate
1MiB aligned 1MiB with rte_malloc_socket when DPDK is built with ASan.

Enter try_expand_heap_primary with pg_sz=0x200000, elt_size=0x100000,
align=0x100000
alloc_sz is set to 0x200000
Enter alloc_pages_on_heap
Enter find_suitable_element
Enter elem_start_pt with elem of size 0x200000
MALLOC_ELEM_TRAILER_LEN is non zero because of ASan
new_data_start is equal to elem because of alignment
There is no room for the header and it fails.

If my analysis is correct the formula used in try_expand_heap_primary to
compute alloc_sz is off. I suggest something like:

alloc_sz = RTE_ALIGN_CEIL(RTE_ALIGN_CEIL(elt_size + MALLOC_ELEM_TRAILER_LEN,
align) + MALLOC_ELEM_HEADER_LEN, pg_sz);

I am working with branch 21.11, but I think this issue affects all the branches
which contain commit f92b9ebed03dbd140a5a7b921cb898e661a59068