Allow using external memory without malloc

Currently, the only way to use externally allocated memory is through rte_malloc API's. While this is fine for a lot of use cases, it may not be suitable for certain other use cases like manual memory management, etc.

This patchset adds another API to register memory segments with DPDK (so that API's like ``rte_mem_virt2memseg`` could be relied on by PMD's and such), but not create a malloc heap out of them.

Aside from the obvious (not adding memory to a heap), the other major difference between this API and the ``rte_malloc_heap_*`` external memory functions is the fact that no DMA mapping is performed automatically, as well as no mem event callbacks are triggered.

This really draws a line in the sand, and there are now two ways of doing things - do everything automatically (using the ``rte_malloc_heap_*`` API's), or do everything manually (``rte_extmem_*`` and future DMA mapping API [1] that would replace ``rte_vfio_dma_map``). This way, the consistency of API is kept, and flexibility is also allowed.

[1] https://mails.dpdk.org/archives/dev/2018-November/118175.html

v3:
- Rebase on latest master

v2:
- More sanity checking of parameters

Anatoly Burakov (4):
malloc: separate creating memseg list and malloc heap
malloc: separate destroying memseg list and heap data
mem: allow registering external memory areas
mem: allow usage of non-heap external memory in multiprocess

 .../prog_guide/env_abstraction_layer.rst      |  63 +++++++--
 doc/guides/rel_notes/release_19_02.rst        |   7 +
 lib/librte_eal/common/eal_common_memory.c     | 119 +++++++++++++++++
 lib/librte_eal/common/include/rte_memory.h    | 122 ++++++++++++++++++
 lib/librte_eal/common/malloc_heap.c           | 104 +++++++++++----
 lib/librte_eal/common/malloc_heap.h           |  15 ++-
 lib/librte_eal/common/rte_malloc.c            | 116 +++++++----------
 lib/librte_eal/rte_eal_version.map            |   4 +
 8 files changed, 447 insertions(+), 103 deletions(-)

2.17.1