examples/netmap_compat: fix makefile
examples/netmap_compat: fix makefile

It is not allowed to reference a an absolute file name in SRCS-y.
A VPATH has to be used, else the dependencies won't be checked
properly.

Signed-off-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>
Acked-by: Thomas Monjalon <ee2fa8b2681c737f775687e475dcbf2028a412f1@6wind.com>

mixja/dpdk,mixja/dpdk,venkynv/dpdk-mirror,msune/dpdk,venkynv/dpdk-mirror,mixja/dpdk,tsphillips/dpdk-fork,msune/dpdk,john-mcnamara-intel/dpdk,tsphillips/dpdk-fork,venkynv/dpdk-mirror,venkynv/dpdk-mirror,msune/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,msune/dpdk,john-mcnamara-intel/dpdk,mixja/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork