toolchainfile.cmake: only search the sysroot for CMake module

This change prevents CMake from searching outside the sysroot location
for CMake modules when cross-compiling.

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Reviewed-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/misc/toolchainfile.cmake.in

@@ -21,6 +21,7 @@ set(CMAKE_INSTALL_SO_NO_EXE 0)
 set(CMAKE_PROGRAM_PATH "${RELOCATED_HOST_DIR}/usr/bin")
 set(CMAKE_FIND_ROOT_PATH "${RELOCATED_HOST_DIR}/@@STAGING_SUBDIR@@")
 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 set(ENV{PKG_CONFIG_SYSROOT_DIR} "${RELOCATED_HOST_DIR}/@@STAGING_SUBDIR@@")