Add options to link with external DPDK tree

By uncommenting following lines in the build-data/platforms/vpp.mk
VPP links nicely with packaged DPDK 2.2 distributed with
Ubuntu 16.04 LTS.

vpp_uses_external_dpdk = yes
vpp_dpdk_inc_dir = /usr/include/dpdk
vpp_dpdk_lib_dir = /usr/lib
vpp_dpdk_shared_lib = yes

Change-Id: Id5b7d95bac6aa60341933b92e86d949a9abf1a5d
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/build-data/packages/vpp-api-test.mk b/build-data/packages/vpp-api-test.mk
index e26c2e7..38edb5b 100644
--- a/build-data/packages/vpp-api-test.mk
+++ b/build-data/packages/vpp-api-test.mk
@@ -24,7 +24,12 @@
 
 ifneq ($($(PLATFORM)_uses_dpdk),no)
 vpp-api-test_configure_args = --with-dpdk
+ifeq ($($(PLATFORM)_uses_external_dpdk),yes)
+vpp-api-test_CPPFLAGS += -I$($(PLATFORM)_dpdk_inc_dir)
+vpp-api-test_LDFLAGS += -L$($(PLATFORM)_dpdk_lib_dir)
+else
 vpp-api-test_configure_depend += dpdk-install
 vpp-api-test_CPPFLAGS += $(call installed_includes_fn, dpdk)
 vpp-api-test_LDFLAGS += $(call installed_libs_fn, dpdk)
 endif
+endif