build/cmake: fix empty BASE_DEFCONFIG string

Currently CMake system has empty string for BASE_DEFCONFIG option.
This patch fills value for it.

Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>

cmake/nuttx_mkconfig.cmake

@@ -40,6 +40,16 @@ if(COMPARE_RESULT EQUAL 0 AND EXISTS ${CONFIG_H})
   return()
 endif()
 
+set(DEFCONF_VAL "${NUTTX_BOARD}/${NUTTX_CONFIG}")
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E compare_files ${CMAKE_BINARY_DIR}/.config
+          ${CMAKE_BINARY_DIR}/.config.orig
+  RESULT_VARIABLE COMPARE_RESULT
+  WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
+if(COMPARE_RESULT)
+  set(DEFCONF_VAL "${DEFCONF_VAL}-dirty")
+endif()
+
 set(DEQUOTELIST
     # NuttX
     "CONFIG_DEBUG_OPTLEVEL" # Custom debug level
@@ -81,11 +91,16 @@ file(APPEND ${CONFIG_H} "#define CONFIG_y 1\n")
 file(APPEND ${CONFIG_H} "#define CONFIG_m 2\n\n")
 file(APPEND ${CONFIG_H}
      "/* General Definitions ***********************************/\n")
+file(APPEND ${CONFIG_H} "#define CONFIG_BASE_DEFCONFIG \"${DEFCONF_VAL}\"\n")
 
 file(STRINGS ${CMAKE_BINARY_DIR}/.config ConfigContents)
 foreach(NameAndValue ${ConfigContents})
   string(REGEX REPLACE "^[ ]+" "" NameAndValue ${NameAndValue})
   string(REGEX MATCH "^CONFIG[^=]+" NAME ${NameAndValue})
+  # skip BASE_DEFCONFIG here as it is handled above
+  if("${NAME}" STREQUAL "CONFIG_BASE_DEFCONFIG")
+    continue()
+  endif()
   string(REPLACE "${NAME}=" "" VALUE ${NameAndValue})
   if(NAME AND NOT "${VALUE}" STREQUAL "")
     if(${VALUE} STREQUAL "y")