eal: build with meson

eal: build with meson

Support building the EAL with meson and ninja. This involves a number of
different meson.build files for iterating through all the different
subdirectories in the EAL. The library itself will be compiled on build but
the header files are only copied from their initial location once "ninja
install" is run. Instead, we use meson dependency tracking to ensure that
other libraries which use the EAL headers can find them in their original
locations.

Note: this does not include building kernel modules on either BSD or Linux

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>
Acked-by: Luca Boccassi <luca.boccassi@gmail.com>