This patch converts the memory-allocator interfaces ('Allocator',
'Range_allocator') and their implementations ('Heap', 'Sliced heap',
'Slab', 'Allocator_avl', 'Synced_allocator') to the new 'Allocation'
utility. The new interface resides at base/memory.h whereas the
traditional allocators implement the new interface.
Down the road, the traditional allocators can successively be decoupled
from the traditional 'Allocator' and 'Range_allocator' interfaces.
Issue #5502
Issue #5245
Override 'try_alloc/free' because ethernet frame headers are 14 bytes
(src/dst mac (12) + ethertype (2)) causing the IP header to be 2 byte
aligned, leading to problems on platforms that require load/store
operations to be naturally aligned when reading, for example, 4 byte IP
addresses. Therefore, we align the allocation to 2 bytes, so the IP
header is aligned to 4.
issue #4312
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
