compat: fix symbol version support with meson

compat: fix symbol version support with meson

For meson builds, the define to enable the symbol version
macros in rte_compat.h was missing. This led to symbols being
omitted from shared objects. For example, checking rte_distributor.so
with objdump and comparing make and meson built versions:

$ objdump -T make-build/lib/librte_distributor.so | grep _flush
 0000000000001b60 g    DF .text	00000000000000a7 (DPDK_2.0)   rte_distributor_flush
 0000000000003f10 g    DF .text	0000000000000434  DPDK_17.05  rte_distributor_flush
$ objdump -T meson-build/lib/librte_distributor.so | grep _flush
 0000000000001d50 g    DF .text	00000000000000fb  DPDK_2.0    rte_distributor_flush

Adding in the missing define fixes this.

Fixes: 5b9656b157d3 ("lib: build with meson")
Cc: stable@dpdk.org
Reported-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Tested-by: Luca Boccassi <bluca@debian.org>