Always use 'lib' instead of 'lib64'

It is packaging responsibility to put libs in the right place.
Use of lib64 resulted in huge amount of files with hardcoded lib64.
This patch simplifies things...

Change-Id: Iab0dea0583e480907732c5d2379eb951a00fa9e6
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/cmake/plugin.cmake b/src/cmake/plugin.cmake
index c6f551d..39c940d 100644
--- a/src/cmake/plugin.cmake
+++ b/src/cmake/plugin.cmake
@@ -69,13 +69,13 @@
       LIBRARY_OUTPUT_DIRECTORY ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/vpp_api_test_plugins)
     install(
       TARGETS ${test_plugin_name}
-      DESTINATION ${VPP_LIB_DIR_NAME}/vpp_api_test_plugins
+      DESTINATION lib/vpp_api_test_plugins
       COMPONENT ${PLUGIN_COMPONENT}
     )
   endif()
   install(
     TARGETS ${plugin_name}
-    DESTINATION ${VPP_LIB_DIR_NAME}/vpp_plugins
+    DESTINATION lib/vpp_plugins
     COMPONENT ${PLUGIN_COMPONENT}
   )
 endmacro()