build: don't hardcode triplet, allow specifying custom lib dir

Type: fix
Change-Id: I33f364fda88914f88f9b976cb83e6d3ff466f0bb
Signed-off-by: Damjan Marion <damarion@cisco.com>
Signed-off-by: Ray Kinsella <mdr@ashroe.eu>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7bb5caa..0448a5b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -33,6 +33,10 @@
   endmacro()
 endif()
 
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR AND EXISTS "/etc/debian_version")
+  set(CMAKE_INSTALL_LIBDIR "lib/${CMAKE_LIBRARY_ARCHITECTURE}")
+endif()
+
 include(CheckCCompilerFlag)
 include(CheckIPOSupported)
 include(GNUInstallDirs)
@@ -152,7 +156,7 @@
 ##############################################################################
 option(VPP_SET_RPATH "Set rpath for resulting binaries and libraries." ON)
 if(VPP_SET_RPATH)
-  set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
+  set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${VPP_LIBRARY_DIR}")
 endif()
 set(CMAKE_INSTALL_MESSAGE NEVER)