Use target compiler for generating lua exported definitions (#7186)

Include the lua subdirectory only after CMAKE_C_COMPILER has been
set to the cross compiler. Otherwise, cmake will use the build machine
compiler to preprocess dataconstants.h, which breaks on some systems
and can cause problems due to different machine dependent types.

radio/src/CMakeLists.txt

@@ -146,7 +146,6 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 include_directories(${CMAKE_CURRENT_BINARY_DIR}/bitmaps/${GUI_DIR})
 
-add_subdirectory(lua)
 include(gui/CMakeLists.txt)
 
 if(RTC_BACKUP_RAM)
@@ -551,3 +550,7 @@ if(NOT MSVC)
   PrintTargetReport("firmware")
 
 endif(NOT MSVC)
+# Include the lua subdirectory after CMAKE_C_COMPILER has been
+# set. Otherwise, the custom commands it includes will use the
+# default CMAKE_C_COMPILER instead of the one we set manually
+add_subdirectory(lua)