add _python_* variables for host

config/functions

@@ -141,6 +141,9 @@ setup_toolchain() {
       export CXX_FOR_BUILD="$CXX"
       export BUILD_CC="$CC"
       export BUILD_CXX="$CXX"
+      export _python_sysroot="$TOOLCHAIN"
+      export _python_prefix=/
+      export _python_exec_prefix=/
       ;;
   esac
 }