mem: move librte_malloc to eal/common

mem: move librte_malloc to eal/common

Move malloc inside eal and create a new section in MAINTAINERS file for
Memory Allocation in EAL.

Create a dummy malloc library to avoid breaking applications that have
librte_malloc in their DT_NEEDED entries.

This is the first step towards using malloc to allocate memory directly
from memsegs. Thus, memzones would allocate memory through malloc,
allowing to free memzones.

Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>