common/mlx5: add Windows meson file

common/mlx5: add Windows meson file

File drivers/common/mlx5/windows/meson.build is added to enable mlx5
source files compilation under common windows directory.
A Devx SDK tool must be installed to export two external H files:
mlx5devx.h and mlx5_ifc_devx.h. The installation is based on environment
variable DEVX_INC_PATH. In addition a DLL lib file is installed based on
environment variable DEVX_LIB_PATH. The meson file is using the
environment variables for compilation and linkage.

Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>