net/mlx4: fix build on ppc64

net/mlx4: fix build on ppc64

The AltiVec header file breaks boolean type:

error: incompatible types when initializing type
'__vector _bool int' {aka '_vector(4) __bool int'} using type 'int'

If __APPLE_ALTIVEC__ is defined, then bool type is redefined
and conflicts with stdbool.h.

There is no good solution to fix it for the whole project without
breaking something else, so a workaround is inserted in mlx5 PMD.
This workaround is not compatible with C++ but there is no C++ in DPDK.

Related to: 725f5dd0bfb5 ("net/mlx5: fix build on PPC64")
Cc: stable@dpdk.org
Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Tested-by: David Christensen <drc@linux.vnet.ibm.com>
Acked-by: Matan Azrad <matan@mellanox.com>