cmake: initial cross-compilation support

Change-Id: Ib9c2aba1eda08a22465441e33553b9b744c79d56
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index fedf931..b404b50 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -33,6 +33,16 @@
 list(GET VPP_LIB_VERSION 0 VPP_LIB_VERSION)
 
 ##############################################################################
+# cross compiling
+##############################################################################
+if(CMAKE_CROSSCOMPILING)
+  set(CMAKE_IGNORE_PATH
+    /usr/lib/${CMAKE_HOST_SYSTEM_PROCESSOR}-linux-gnu/
+    /usr/lib/${CMAKE_HOST_SYSTEM_PROCESSOR}-linux-gnu/lib/
+  )
+endif()
+
+##############################################################################
 # build config
 ##############################################################################
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
@@ -123,6 +133,7 @@
 pr("GIT toplevel dir" "${VPP_GIT_TOPLEVEL_DIR}")
 pr("C flags" "${CMAKE_C_FLAGS}")
 pr("Linker flags" "${CMAKE_LINKER_FLAGS}")
+pr("Host processor" "${CMAKE_HOST_SYSTEM_PROCESSOR}")
 pr("Target processor" "${CMAKE_SYSTEM_PROCESSOR}")
 pr("Build type" "${CMAKE_BUILD_TYPE}")
 pr("Prefix path" "${CMAKE_PREFIX_PATH}")