fix for ESP32 cores > 2.0.0

Author: technyon

Arduino-toolchain.cmake

@@ -91,6 +91,9 @@ set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM BOTH)
 set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 
+# Workaround for CMAKE_TRY_COMPILE_TARGET_TYPE. For later ESP32 cores this file is missing
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/build_opt.h" "")
+
 # Do not try to link during the configure time, due to the dependency on the
 # core, which we do not have a target yet.
 set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)