cmake/sched: fix build break based on mainline

Signed-off-by: chao an <anchao@xiaomi.com>

CMakeLists.txt

@@ -65,6 +65,13 @@ if(NOT DEFINED BOARD_CONFIG)
   message(FATAL_ERROR "Please define configuration with BOARD_CONFIG")
 endif()
 
+find_program(KCONFIGLIB olddefconfig)
+if(NOT KCONFIGLIB)
+  message(
+    FATAL_ERROR "Kconfig environment depends on kconfiglib, Please install:
+  $ pip install kconfiglib")
+endif()
+
 if(EXISTS ${BOARD_CONFIG} AND EXISTS ${BOARD_CONFIG}/defconfig)
   get_filename_component(NUTTX_BOARD_ABS_DIR ${BOARD_CONFIG} ABSOLUTE BASE_DIR
                          ${NUTTX_DIR})